dy/dx=(dy/du)(du/dx)
(a) dy/dx=2(⅔(2u-2)^-⅓)(12x²)=
16x²(2u-2)^-⅓=16x²(8x³+2-2)^-⅓=(16x²)(8x³)^-⅓=16x²/2x=8x.
(b) dy/dx=(1/√(2√(u+2))(4)=2/√(4x)=1/√x or √x/x.
[Another way by direct substitution:
(a) y=(8x³)^⅔=4x², dy/dx=8x.
(b) y=√(4x)=2√x, dy/dx=1/√x or √x/x (rationalised)]
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