Show work and explain with formulas.

10. find the sum (see picture).

11. find the sum of the geometric series: a_2 = -36, a_5 = 972, n = 7

12. find the first term: s_n = 315, a_n = 5, r = 1/2, n = 6

Step-by-step explanation:

10.

The formula of a sum of terms of a geometric sequence:

We have:

Therefore:

Substitute a₁ = 5, r = 2 and n = 9:

==========================================

11.

We have

We know:

Therefore

Substitute:

Calculate the first term:

Put a₁ = 12, r = -3 and n = 7 to the formula of a sum:

==========================================

12.

We have

We know:

Substitute:

Check for the given sum:

Substitute a₁ = 160, r = 1/2 and n = 6:

CORRECT :)

answer: i think one of the answer is $150 and $300?

step-by-step explanation:

all you should have to do is insert 1 where the c is, representing that one car is sold.

f(c) = 250c + 500

f(1) = 250(1) + 500

f(1) = 250 + 500

f(1) = 750

he earns $750 for each car sold.

hope this you! have a happy , here's a turkey!