y=x^4-6x^3+12x^2-10
y'=4x^3-18x^2+24x=4x(x^2-9x/2+6)=4x[(x-9/4)^2+15/16]
y'>0时,x>0,y的严格单调减区间为(0,+∞)
y'0,x>2或x