图
y=(x-1)^2*(x-2)^3y'=2(x-1)(x-2)^3+3(x-1)^2(x-2)^2=(x-1)(x-2)^2[2(x-2)+3((x-1)]=(x-1)(x-2)^2(5x-7)y'>0==>x7/5y'1
