(1)分母若是x^3-8,答案為1/3;否則答案是0
(2)0
(3)(2x/5)*(x^2+1)^(-4/5)
(4)1/2
(5)x=0,max=6;x=2,min=-2
(6)lim (f(x+h)-f(x))/h=lim (x+h)^2-1-x^2+1
h->0 h->0
lim (2x+h)=2x
h->0
(7)2xdx-8xydx-4x^2dy+dy=0
dy/dx=(2x-8xy)/(4x^2-1)
at (1,0),dy/dx=2/3
(8)if x=2,the tank has max volume