# What the value of n ?

RauLiTo
Your question is ill defined. If you mean "What value of n satisfies this FOR ALL X?" then there isn't one. You can see this by working out the coefficent of $$x^{3}$$ in $$(x+2)^{n}+(2-x)^{n}$$ and working out what value of n gives that coefficent as -1, so that it cancels with the $$x^{3}$$ term. Unfortunately, this leaves you with other terms which don't cancel (linear ones).