f(x)=x平方-3x+2则f(sinx+1)等于多少
问题描述：
f(x)=x平方-3x+2则f(sinx+1)等于多少
答
f(x)=x^2-3x+2=(x-1)(x-2)
令sinx+1=t
f(t)=(t-1)(t-2)
还原t后得
f(sinx+1)=(sinx+1-1)(sinx+1-2)
=sinx(sinx-1)
=sin^2x-sinx