Đáp án:
a, y'=x^2-8x^3+4
b, y'=-4x^2-12x-9
c, y'=(x^2-8x+9)'*(x-5)-(x^2-8x+9)*(x-5)'/(x-5)^2
=(2x-8)*(x-5)-(x^2-8x+9)*1/(x-5)^2
=2x^2-10x-8x+40-x^2+8x-9/(x-5)^2
=x^2-10x+31/(x-5)^2
d, y'=(x^3-2x+3)'/2 căn x^3-2x+3
= 3x^2-2/2 căn x^3-2x+3
e, y'=-1/(x+1)^2-2
