Question

1) Find the indicated term of the arithmetic sequence with the first term a1 and the common difference d.
a. Find a7 when a1 = –8 and d = 4.
b. Find a16 when a1 = 10 and d = 7.

Answer 1

Hi!

The general formula of AP:

$a + (n - 1)d = an$

1.

$a + (n - 1)d \\ - 8 + (7 - 1)(4) = a7\\ - 8 + 6(4) = a7 \\ - 8 + 24 = a7 \\ 16 = a7$

2.

$a + (n - 1)d \\ 10 + (16 - 1)(7) = a16 \\ 10 + 15(7) = a16 \\ 10 + 105 = a16 \\ 110 = a16$

Thanks ❤