Arithmetic Sequence
Find:'nth' term of each
i)n^2+2n
ii) n^2- 2n
Solution:1) Sum of first n terms = n² + 2n
We know that,
Sum of first n terms = n/2 * [ a + l ]
Where,
a is first term
l is nth or last term.
Substitute n = 1 to find the sum of first 1 terms i.e., first term (a) of the AP.
→ S₁ = a = (1)² + 2(1)
→ a = 1 + 2
→ a = 3
Hence,
→ n/2 * [ a + l ] = n² + 2n
→ a + l = n(n + 2) * 2/n
→ a + l = 2n + 4
→ l = 2n + 4 - a
→ l = 2n + 4 - 3
→ l = 2n + 1
Hence, the nth term is 2n + 1.
2)S(n) = n² - 2n
→ S₁ = a = (1)² - 2(1)
→ a = - 1
Hence,
→ n/2 * [ - 1 + l ] = n² - 2n
→ l - 1 = n(n - 2) * 2/n
→ l - 1 = 2n - 4
→ l = 2n - 4 + 1
→ l = 2n - 3
Hence, the nth term is 2n - 3.
I hope it will help you.
Regards.
Step-by-step explanation:
Series
The series of a sequence is the sum of the sequence to a certain number of terms. It is often written as Sn. So if the sequence is 2, 4, 6, 8, 10, ... , the sum to 3 terms = S3 = 2 + 4 + 6 = 12.
The Sigma Notation
The Greek capital sigma, written S, is usually used to represent the sum of a sequence. This is best explained using an example:
This means replace the r in the expression by 1 and write down what you get. Then replace r by 2 and write down what you get. Keep doing this until you get to 4, since this is the number above the S. Now add up all of the term that you have written down.
This sum is therefore equal to 3×1 + 3×2 + 3×3 + 3×4 = 3 + 6 + 9 + 12 = 30.
3
S 3r + 2
r = 1
This is equal to:
(3×1 + 2) + (3×2 + 2) + (3×3 + 2) = 24 .
The General Case
n
S Ur
r = 1
This is the general case. For the sequence Ur, this means the sum of the terms obtained by substituting in 1, 2, 3,... up to and including n in turn for r in Ur. In the above example, Ur = 3r + 2 and n = 3.
Arithmetic Progressions
An arithmetic progression is a sequence where each term is a certain number larger than the previous term. The terms in the sequence are said to increase by a common difference, d.
For example: 3, 5, 7, 9, 11, is an arithmetic progression where d = 2. The nth term of this sequence is 2n + 1 .
In general, the nth term of an arithmetic progression, with first term a and common difference d, is: a + (n - 1)d . So for the sequence 3, 5, 7, 9, ... Un = 3 + 2(n - 1) = 2n + 1, which we already knew.
The sum to n terms of an arithmetic progression
This is given by:
Sn = ½ n [ 2a + (n - 1)d ]
You may need to be able to prove this formula. It is derived as follows:
The sum to n terms is given by:
Sn = a + (a + d) + (a + 2d) + … + (a + (n – 1)d) (1)
If we write this out backwards, we get:
Sn = (a + (n – 1)d) + (a + (n – 2)d) + … + a (2)
Now let’s add (1) and (2):
2Sn = [2a + (n – 1)d] + [2a + (n – 1)d] + … + [2a + (n – 1)d]
So Sn = ½ n [2a + (n – 1)d]
Example
Sum the first 20 terms of the sequence: 1, 3, 5, 7, 9, ... (i.e. the first 20 odd numbers).
S20 = ½ (20) [ 2 × 1 + (20 - 1)×2 ]
= 10[ 2 + 19 × 2]
= 10[ 40 ]
= 400
Geometric Progressions
A geometric progression is a sequence where each term is r times larger than the previous term. r is known as the common ratio of the sequence. The nth term of a geometric progression, where a is the first term and r is the common ratio, is:
arn-1
For example, in the following geometric progression, the first term is 1, and the common ratio is 2:
1, 2, 4, 8, 16, ...
The nth term is therefore 2n-1
The sum of a geometric progression
The sum of the first n terms of a geometric progression is:
a(1 - rn )
1 – r
We can prove this as follows:
Sn = a + ar + ar2 + … + arn-1 (1)
Multiplying by r:
rSn = ar + ar2 + … + arn (2)
(1) – (2) gives us:
Sn(1 – r) = a – arn (since all the other terms cancel)
And so we get the formula above if we divide through by 1 – r .
Example
What is the sum of the first 5 terms of the following geometric progression: 2, 4, 8, 16, 32 ?
S5 = 2( 1 - 25)
1 - 2
= 2( 1 - 32)
-1
= 62
The sum to infinity of a geometric progression
In geometric progressions where |r| < 1 (in other words where r is less than 1 and greater than –1), the sum of the sequence as n tends to infinity approaches a value. In other words, if you keep adding together the terms of the sequence forever, you will get a finite value. This value is equal to:
a
1 – r
Example
Find the sum to infinity of the following sequence:
1 , 1 , 1 ,
1
,
1
,
1
, ...
2 4 8 16 32 64
Here, a = 1/2 and r = 1/2
Therefore, the sum to infinity is 0.5/0.5 = 1 .
So every time you add another term to the above sequence, the result gets closer and closer to 1.
Harder Example
The first, second and fifth terms of an arithmetic progression are the first three terms of a geometric progression. The third term of the arithmetic progression is 5. Find the 2 possible values for the fourth term of the geometric progression.
The first term of the arithmetic progression is: a
The second term is: a + d
The fifth term is: a + 4d
So the first three terms of the geometric progression are a, a + d and a + 4d .
In a geometric progression, there is a common ratio. So the ratio of the second term to the first term is equal to the ratio of the third term to the second term. So:
a + d = a + 4d
a a + d
(a + d)(a + d) = a(a + 4d)
a² + 2ad + d² = a² + 4ad
d² - 2ad = 0
d(d - 2a) = 0
therefore d = 0 or d = 2a
The common ratio of the geometric progression, r, is equal to (a + d)/a
Therefore, if d = 0, r = 1
If d = 2a, r = 3a/a = 3
So the common ratio of the geometric progression is either 1 or 3 .
Solve for f 7a - 3d + 6f = 5
Answer:
f = 5/6 - 7a/6 + d/2
Step-by-step explanation:
Suppose that grade point averages of undergraduate students at one university have a bell-shaped distribution with a mean of 2.51 and a standard deviation of 0.44. Using the empirical rule, what percentage of the students have grade point averages that are no more than 2.07? Please do not round your answer.
Answer:
15.87%
Step-by-step explanation:
Given that :
Mean (m) = 2.51
Standard deviation (σ) = 0.44
Percentage of students with grade point average no more than 2.07
Using the relation :
Zscore = (X - mean) / standard deviation
X = 2.07
Zscore = (2.07 - 2.51) / 0.44
Zscore = - 0.44 / 0.44
Zscore =. - 1
P(Z < - 1) : using the z table
P(Z < 1) = 0.1587
Hence, Percentage of students with grade point average no more than 2.07 is (0.1587 * 100%) = 15.87%
Amanda is making white oatmeal cookies with raisins and pecans for her club. The recipe makes seventeen of the big, chewy kind of oatmeal cookies with lots of raisins and nuts. It takes one-fourth of a cup of nuts and one-half of a cup of raisins just for the seventeen cookies! There are thirty-four members in Amanda's club. If she makes exactly thirty-four cookies, how many cups of nuts will she need?
Answer:
half a cup
Step-by-step explanation:
if one fourth is needed for 17 and thirty four is the double of 17, then
1/4 x 2 = 2/4
2/4 simplified is 1/2->half
i need help with this question. please help me.
Answer:
it cost $9.2972048
Step-by-step explanation:
Answer:
Coach brought 2 orders of fries to the table, and all three orders of fries cost him $6.
Which one?
A. B. C. or
Answer:
C
Step-by-step explanation:
Answer:
C
Step-by-step explanation:
Not sure how to do this
Hannah is making cookies. Each batch of cookies uses 3/4 lbs of butter. She is going to make 5 batches. How much butter will she need?
Answer:3/4*5=3 3/5
Step-by-step explanation:
The graph below shows a proportional relationship between xxx and yyy.
What is the constant of proportionality,
x
y
start fraction, y, divided by, x, end fraction ?
0.50
Step-by-step explanation:
Its right <3
In the graph the constant of proportionality is 0.5
What is Graph?Graph is a mathematical representation of a network and it describes the relationship between lines and points.
The constant of proportionality is the ratio between two directly proportional quantities.
Two quantities are directly proportional when they increase and decrease at the same rate.
The constant of proportionality k is given by k=y/x where y and x are two quantities that are directly proportional to each other.
From the given graph let us take one point (1, 0.5)
k=0.5/1
Constant of proportionality is 0.5
Hence, in the graph the constant of proportionality is 0.5
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EVALUATE
9(6−2.4)−10
Answer:
The answer is 22.4.
Answer:
22.4
Step-by-step explanation:
you multiply 6 and -2.4 by 9
that gives you 54 and -21.6
then you add -10 to -21.6 giving you -31.6
lastly subtract -31.6 out of 54
which gives you 22.4
help me pleaseeeeeeeeeeeee
Answer:
Parallel
Step-by-step explanation:
The run right by each other not touching
Answer:
parallel
Step-by-step explanation:
What is the equation of the line ? and how do i know ?
Answer:
The equation of the line is y=-16x+7
Step-by-step explanation:
I am not totally sure if that is what you meant by the equation of the line but that is my answer. I can change it if you are more specific.
Anyways, you need to find the slope because you already know the y-intercept, 7.
Slope=rise/run between two pretty points( A point that lines up on the grid)
So you must go from the bottom point and count how ever many are separating the two points. It turned out to be 16 and since the line is going down it is a negative. You then plug the numbers into the slope intercept form and that is your answer.
help I’ll award brainliest
Answer:
Most likely the answer hope this helps :P
Step-by-step explanation:
1= 10
2= 20
5 = 50
8 = 80
X = 100
Solve −3.5 = x/4 for x using the multiplication property of equality.
The operation in the problem is
-Addition
-Subtraction
-Multiplication
-Divison
The inverse operation is
-Addition
-Subtraction
-Multiplication
-Divison
= x
0.5
-7.5
-12
-14
Answer:
Step-by-step explanation:
The operation in the problem is division
The inverse is multiplication
(-14)
Answer: division inverse= multiplication answer=-14
Step-by-step explanation:
Lemme put y’all on this app called Cymath. It answers the questions and explains the steps
If (ax^2 + 3x + 2b) - (5x^2+bx-3c)=3x^2-9, what is the value of A + B + C?
Answer:
We have the equation:
(ax^2 + 3x + 2b) - (5x^2+bx-3c)= 3x^2 - 9
First, move all to the left side.
(ax^2 + 3x + 2b) - (5x^2+bx-3c) - 3x^2 + 9 = 0
Now let's group togheter terms with the same power of x.
(a - 5 - 3)*x^2 + (3 - b)*x + (2b + 3c + 9) = 0.
This must be zero for all the values of x, then the things inside each parenthesis must be zero.
1)
a - 5 - 3 = 0
a = 3 + 5 = 8.
2)
3 - b = 0
b = 3.
3)
2b + 3c + 9 = 0
2*3 + 3c + 9 = 0
3c = -6 - 9 = -15
c = -15/3 = -5
Then we have:
a = 8, b = 3, c = -5
a + b + c = 8 + 3 - 5 = 6
Jonathan forgot his math homework on the kitchen table and left for school without it. He biked at the speed of 15 mph. His mother saw the homework when he was already 1 mile from home, and started chasing him. She drove at a speed of 25 mph and caught him at the school entrance. How far is the school from Jonathan's home?
Answer:
The school is 1.5 miles away from Jonathan's home
Step-by-step explanation:
Let D be the distance remaining after 1 mile
We are given that He biked at the speed of 15 mph. His mother saw the homework when he was already 1 mile from home, and started chasing him. She drove at a speed of 25 mph and caught him at the school entrance.
So, Time taken to cover D distance by Son is equal to the time taken by mother from home to school entrance(D+1) since she caught him at school entrance
Speed of Jonathan bike = 15 mph
Speed of Mother's bike = 25 mph
So, [tex]\frac{D}{15}=\frac{D+1}{25}[/tex]
25D=15D+15
10D=15
D=1.5
So, the school is 1.5 miles away from Jonathan's home
Pls help..it is an emergency...
Thank u
Answer:
Triangle A did a reflection over the x-axis and the translated down two units to become triangle B
Step-by-step explanation:
Hope this helps. Happy Halloween
this is the picture that goes with my question.
Answer:
first u should make your equation: y= -1/5 (x-5) - 3
y= -1/5x +1 -3
y= -1/5 x -2
then u should setting some number like 1 ,2 ..... instead of *x* and when u done this u should dissolve it (now your *y* is came out too) so you have your x,y now
According to the points you get, you put it on the chart and connect it
if you do not understand something, tell me to draw on paper so you can understand better
Square EFGH will be translated 3 units up and 5 units right. What will be the coordinates of the image point F?
Answer:
(3,2)
Step-by-step explanation:
I hope this helps : )
Students was 1: 8. However, this year the ratio of the number of middle school students to the number of high school students changed to 2: 7. If there are 18 middle school students in the band this year, how many fewer high school students are in the band this year compared to last year? Expla
Answer:
Step-by-step explanation:
Last year
Ratio of the number of middle school students to number of high school students = 1 : 8
Total ratio = 9
Middle school = 1
High school = 8
Total students in the band = x
Middle school = 1/9x
High school = 8/9x
Total = 1/9x + 8/9x
This year
Ratio of the number of middle school students to number of high school students = 2 : 7
Total ratio = 9
Middle school = 2
High school = 7
Total students = x
Middle school = 2/9x
High school = 7/9x
Total = 2/9x + 7/9x
If there are 18 middle school students in the band this year
2/9x = 18
x = 18÷2/9
= 18 × 9/2
= 81
x = 81
Last year:
1/9x + 8/9x
= 1/9 * 81 + 8/9 * 81
= 9 + 72
= 81
This year
2/9x + 7/9x
2/9*81 + 7/9*81
= 18 + 63
=81
Change in middle school =this year - last year
= 18 - 9
= 9 (increase)
Change in high school = this year - last year
= 63 - 72
= -9 (decrease)
sid has £5 to buy apples and bananas
Answer:
So he could use 3 pounds for apples, and two for bananas.
Step-by-step explanation:
(4+3c^5)(4-3c^5) combine like terms
Answer:
16 − 9 c ^10
Step-by-step explanation:
Simplify the expression.
Answer:
-9c^10+16
Step-by-step explanation:
(4+3c^5)(4-3c^5) multiply
(16 -12c^5+12c^5-9c^10) combine and rewrite
-9c^10+16
cell phone company A charges an $80 deposit and $10 each.month for unlitmited service.cell phone company Charges a $70 deposit and $12 each month for unlimited service.after how many months will cell phone company A cost more then cell phone company B?
In an electrical circuit, the voltage across a resistor is directly proportional to the current running through the resistor. If a current of 12 amps produces 480 volts across a resistor, how many volts would a current of 1.5 amps produce across an identical resistor? Record your answer as number only.
Answer:volts =60v
Step-by-step explanation:
STEP 1
The voltage across a resistor is directly proportional to the current running through the resistor Is mathematically represented as
V∝ C
introducing the proportion of constant , we have
V=KC
Step 2
When current =12 amps, and volts = 480, we have
V=kC
480=K X 12
Constant of proportionality ,K= V/C=480/12= 40
Therefore, when current = 1.5 amp, volts=?
V= KC
V= 40 X 1.5
V= 60 volts
my sister asked if you guys can solve this out for her. thanks
Answer:
Part 1: 10, Part 2: 6
Step-by-step explanation:
Solve the equation s = a + lw for the variable w
Answer:
w= [tex]\frac{-a+s}{l}[/tex]Step-by-step explanation:
Let's solve for w.
s=a+lw
Step 1: Flip the equation.
lw+a=s
Step 2: Add -a to both sides.
lw+a+−a=s+−a
lw=−a+s
Step 3: Divide both sides by l
[tex]\frac{lw}{l} =\frac{-a+s}{l}[/tex]
2) Write the equation of a line that passes through the point (-4,-5) and is perpendicular to a line that passes through the points (-6, 8) and (10,0).
Answer:
y= - 1/4x
Step-by-step explanation:
The equation of the line passing through that point with the required slope is y=2x+3.
What is slope?The slope of a line is the change in the y-coordinate relative to the change in the x-coordinate. The net change in the y-coordinate is indicated by Δy and the net change in the x-coordinate by Δx. Thus, the change in y-coordinate with respect to change in x-coordinate is given by: m = change in y/change in x = Δy/Δx Where "m" is the slope of the line. The slope of a straight line can also be represented by the formula tan θ = Δy/Δx So, tan θ is the slope of a straight line. In general, the slope of a line indicates its steepness and direction.
Given:
The angle of slope of a line between two points (x1,y1) and (x2,y2) can be easily determined by finding the difference in the coordinates of the points. The slope is usually indicated by the letter "m".
The slope of a line passing through points (x1,y1)and(x2,y2) is given by
m=(y2−y1)/(x2−x1)
The slope ([tex]m^p)[/tex] of a line perpendicular to a line with slope ([tex]m^p)[/tex] is =−1/m because the product of the slopes of two perpendicular lines is -1, except in the pathological case where the lines are parallel to the x and y axis.
slope m of a line, and the coordinates of a known point (x1,y1) it is simple to plug them into the point-slope formula for a line to determine the equation for that line.
y=mx +b
y1=mx1+b
solve for b
Going through those steps:
(x1,y1)=(-6, 8)
(x2,y2)=(10,0)
m=(0-8)(10-(-6))=-0.5
[tex]m^p[/tex]=−1/-0.5= 2
our known point is (−4,−5)
−5=2(−4)+b
-5 = -8+b
b = 3
Therefore, the equation of the line passing through that point with the required slope is y=2x+3.
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Nathan bought 3 1/4 pounds of apples for $0.75 per pound. How much did Nathan pay for the apples (rounded to the nearest hundredth)?
Answer: 2.5
Step-by-step explanation:
3 1.4 lbs also equals 3.25
3 x 0.75 = 2.25
2.25 + 25 = 2.5
A gymnastics school offered a special for enrollment where a new student could enroll for half the price after paying a $17.50 application fee. Twelve new students enrolled, and the school collected $750. Which equation can be used to find p, the regular price of enrollment?
Answer:
12 (p/2 + 17.50) = 750 equation can be used to get regular price of enrollment.
Step-by-step explanation:
So when a new student gets enrolled by paying a $17.50 application fee and gets a value of price halved at p/2
where p = regular price of enrollment
So in reality, for the student to be enrolled he/she must pay = (p/2) + $17.50 application fee to be able to get that special offer.
So Twelve new students enrolled, meaning they paid: 12 (p/2 + 17.50 application fee)
The amount they all paid is $750.
To get the regular price of enrollment from the price that included the application fees, the equation to use would be: 12 (p/2 + 17.50) = 750
The correct answer is 12 ([tex]\frac{p}{2}[/tex] + 17.50) =750
Explanation:
In mathematics, an equation represents equality; this means mathematical expressions are placed to the sides of the equality sign and these have the same value. Moreover, if an equation is written based on a situation or description, the values should include the appropriate mathematical symbols (+, -, x, etc) depending on how each of the factors in the equation relates.
In the case presented, it is known the total collected was $750 and due to this, this value should be placed to one side of the symbol =. Moreover, this value was obtained as students paid 17.50 of the application fee plus half of the price. This can be written as [tex]\frac{p}{2}[/tex] (a half price or price divided 2) + 17.50 (application fee). Finally, these two values should be multiplied by 12 (number of students that paid). According to this, the equation is 12 ([tex]\frac{p}{2}[/tex] + 17.50) =750.
estimate then divide 36712 divided by 52
Answer:
7060 Step-by-step explanatiojo: