Question

If the 1st and 10th terms of geometric sequence are 4 and 100, find the nth term of the sequence

Answer 1

a = 4 first term, r = ?, T10 = 100.

Tn = ar^n - 1 formula for g.p

T10 = 4r^ 10 - 1

100 = 4r^9

Divide both side by 4

100/4 = 4/4r^9

25 = r^9 take the 9th root of both side

9√25 = 9√r^9

r = 9√25

To find the nth term

Since Tn = ar^n - 1