
### Instruction: help me answer this question The coefficients of the (r – 1)th, rth and (r + 1)th terms in the expansion of (x + 1)n are in the ratio 1:3:5. Find n and r., think step by step
### Assistant:  , The answer is By using the general term Tr+1 = nCr an-r br, we can find that n = 7 and r = 3.
