Question

Find the first term of the aritmetic sequence a_27=-1/2 and the common difference is 2.

Answer 1

-105/2

Explanation:

an = a1 + d(n-1) is the equation for an arithmetic sequence

a27 = -1/2

d=2

n =27

substitute in what we know

-1/2 = a1 + 2 (27-1)

-1/2 = a1 +2 * 26

-1/2 = a1 + 52

subtract 52 from both sides

-1/2 -52 = a1

-52 1/2 = a1

-105/2

Explanation:

Answer 2

-52 1/2 = a1

Explanation:

an = a1 + d(n-1) is the equation for an arithmetic sequence

a27 = -1/2

d=2

n =27

substitute in what we know

-1/2 = a1 + 2 (27-1)

-1/2 = a1 +2 * 26

-1/2 = a1 + 52

subtract 52 from both sides

-1/2 -52 = a1

-52 1/2 = a1