求y=(3X⒉+2)(X-5)的导数

y=(3x^2+2)(x-5)
y'=(3x^2+2)'*(x-5)+(3x^2+2)*(x-5)'
=6x(x-5)+1*(3x^2+2)
=6x^2-30x+3x^2+2
=9x^2-30x+2
y=(5x^3-7)(3x+8)=15x^4+40x^3-21x-56
y'=15*4x^3+40*3x^2-21*1-0
=60x^3+120x^2-21
y=x/(x^2+1)
y'=[x'*(x^2+1)-x*(x^2+1)']/(x^2+1)^2
=[(x^2+1)+x*2x]/(x^2+1)^2
=(3x^2+1)/(x^2+1)^2