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问题: 二项式定理,救救我,明天要交

化简
(1+√x)^5+(1-√x)^5

解答:

令t=√x,则原式
=(1+t)^5+(1-t)^5
=(1+5t+10t^2+10t^3+5t^4+t^5)+(1-5t+10t^2-10t^3+5t^4-t^5)
=2+20t^2+10t^4
=2+20x+10x^2.