
### Instruction: help me answer this question The first term of a G.P. is a and the common ratio is r. If the fifth term is 32, and the seventh term is 128, find a and r., think step by step
### Assistant:  , The answer is We have a = a, r = ar^(n–1). Then, a4 = ar^3 = (–3) r^3, a2 = a r^1 = (–3) r. We have (–3) r^3 = [(–3) r]^2 and r = –3, so a7 = a r^7–1 = a r^6 = (–3) (–3)^6 = – (3)^7 = –2187.
