3(y+2/5)=-1/5 What’s y? please help asap!!

Find the nth term of the sequence 7,25,51,85,127

olya-2409 [2.1K]

Let a (n) denote the n-th term of the given sequence.

Check the forward differences, and denote the n-th difference by b (n). That is,

b (n) = a (n + 1) - a (n)

These so-called first differences are

b (1) = a (2) - a (1) = 25 - 7 = 18

b (2) = a (3) - a (2) = 51 - 25 = 26

b (3) = a (4) - a (3) = 85 - 51 = 34

b (4) = a (5) - a (4) = 127 - 85 = 42

Now consider this sequence of differences,

18, 26, 34, 42, …

and notice that the difference between consecutive terms in this sequence b is 8:

26 - 18 = 8

34 - 26 = 8

42 - 34 = 8

and so on. This means b is an arithmetic sequence, and in particular follows the rule

b (n) = 18 + 8 (n - 1) = 8n + 10

for n ≥ 1.

So we have

a (n + 1) - a (n) = 8n + 10

or, replacing n + 1 with n,

a (n) = a (n - 1) + 8 (n - 1) + 10

a (n) = a (n - 1) + 8n + 2

We can solve for a (n) by iteratively substituting:

a (n) = [a (n - 2) + 8 (n - 1) + 2] + 8n + 2

a (n) = a (n - 2) + 8 (n + (n - 1)) + 2×2

a (n) = [a (n - 3) + 8 (n - 2) + 2] + 8 (n + (n - 1)) + 2×2

a (n) = a (n - 3) + 8 (n + (n - 1) + (n - 2)) + 3×2

and so on. The pattern should be clear; we end up with

a (n) = a (1) + 8 (n + (n - 1) + … + 3 + 2) + (n - 1)×2

The middle group is the sum,

$\displaystyle 8\sum_{k=2}^nk=8\sum_{k=1}^nk-8=\frac{8n(n+1)}2-8=4n^2+4n-8$

so that

a (n) = a (1) + (4n ² + 4n - 8) + 2 (n - 1)

a (n) = 4n ² + 6n - 3

4 0

3 years ago

Simplify the expression. (x 3/2)6

Sliva [168]

For this case we must simplify the following expression:

$(x ^ {\frac {3} {2}}) ^ 6$

We have that by definition of properties of powers that is fulfilled:

$(a ^ n) ^ m = a ^ {n * m}$

Then, rewriting the expression:

$x ^ {\frac {3 * 6} {2}} =\\x ^ {\frac {18} {2}} =\\x ^ 9$

Answer:

$(x^{\frac{3}{2}})^6=x^9$

6 0

3 years ago

Solve the system of equations by the addition method { 5x-y=-3 { 4x+3y=-48

Svetach [21]

Answer:

(-3,-12)

Step-by-step explanation:

Multiply the first equation by three to match the second equations y-term

3(5x-y=-3)
4x+3y=-48

15x-3y=-9
4x+3y=-48

The y-terms cancel out

15x=-9
4x=-48

Add the x-terms with each other and the terms after the equal sign as well

19x=-57

Divide -57 by 19

x=-3

Input your x-term (-3) into one of the two first equations and multiply

Either:

5(-3)-y=-3 or

4(-3)+3y=-48

-15-y=-3 or

-12+3y=-48

Simplify your terms

-y=12

3y=-36

Divide

y=-12

y=-12

4 0

3 years ago

A rock is released from rest and freely falls 70 m to the ground. What is its velocity just before impact? A. 1.2 m/s B. 7.0 m/s

Yuri [45]

Answer:

37.04 m/s

Step-by-step explanation:

we can use the equation x = x0 + v0t + 1/2at^2

a = -9.8 m/s^2, the acceleration due to gravity

x0 = 70 m, the starting point of x

v0 = 0 m/s

x = 0

this will allow us to solve for time

0 = 70 + 0 +-4.9t^2

t = 3.779

now we can use the equation v = v0 + at

v = 0 + 9.8(3.77)

v = 37.04 m/s

5 0

3 years ago

14 field goal attempts 12 goals made to what is the success rate

Illusion [34]

Answer:

86%

Step-by-step explanation:

Divide the number of goals made (12) by the number of attempts (14).

12/14 = .857. Round to the nearest hundredth and convert the decimal to a percent.

5 0

3 years ago