y=根号下x+1/（x-1）（x+2）求y的导数

Question

y=根号下x+1/（x-1）（x+2）求y的导数

Answer 1

令f(x)=[x+1/（x-1）（x+2）]^(1/2);
g（x）=x+1/（x-1）（x+2)=x+1/(x^2+x-2);
则y的导数为：(1/2)*(1/f(x))*{1-(2x+1)/[(x^2+x-2)^2]}