Posted by michelle on Thursday, March 1, 2012 at 5:53pm.
dy/dx = dy/du du/dx
du/dx = (1/3)x^-(2/3)
dy/du = [(u-1)-(u+3)]/(u-1)^2
= [(x^(1/3)-1)-(x^(1/3)+3)/(x^(1/3)-1)^2
= -4 / (x^(2/3) -2x^(1/3)+1)
so
dy/du * du/dx
=(-4/3)(x^-(2/3)) /(x^(2/3) -2x^(1/3)+1)
= -4/3(x^4/3-2x +x^(2/3))
luckily 8^(1/3) = 2 :)