Question

杨辉三角形 (1).求(a+b)^5的展开式.(2).用规律计算:2^5-5×2^4+10×2^3-10×2^2+5×2

Answer 1

(a+b)^5

=a^5+5a^4b+10a³b²+10a²b³+5ab^4+b^5

2^5-5×2^4+10×2^3-10×2^2+5×2-1

=(2-1)^5

=1