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

-52 1/2 = a1

Step-by-step 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