
### Instruction: help me answer this question Prove that the coefficient of xn in the expansion of (1 + x)2n is twice the coefficient of xn in the expansion of (1 + x)2n – 1., think step by step
### Assistant:  , The answer is The coefficient of xn in (1+x)2n is 2nCn and the coefficient of xn in (1+x)2n-1 is 2n-1Cn. We need to prove that 2nCn = 2 * 2n-1Cn.
