f(x)=x^2-2x+cos x
, f'(x) = 2x -2 -Sinx
f(x)=3x^4 - 7x^2+2x-1
, f'(x) = 12x^3 -14x +2
f(x)=x^3+3x-sinx
, f'(x) = 3x^2 +3 -Cosx
f(x)=2x^5+4x^3-3x+8
, f'(x) = 10x^4 +12x^2 -3
f(x)=x^3(2x-5) = 2x^4 -5x^3, f'(x) = 8x^3 -15x^2
f(x)=x^4(6x+1)= 6x^5 +x^4, f'(x) = 30x^4 +4x^3