Question

Find a formula for the n th term, T n , of the following arithmetic sequence: − 10 , − 22 , − 34 , − 46 ,. . . Hence, or otherwise, find the value of the 40th term, T 40

Answer 1

T(40) = -478

Explanation:

The first term is -10, that means a = -10

The difference between to first and second term is -12.

Therefore, d = -12.

We may set up the A.S. equation now:

T(n) = a + (n-1)d = -10 + (n-1)(-12)

Now plug in n = 40:

T(40) = -10 + (40-1)(-12) = -478