数学凹凸性与增减性y=1+36x/(x+3)^2y=x^2+1/x求y'和y''.

Question

数学凹凸性与增减性
y=1+36x/(x+3)^2
y=x^2+1/x
求y'和y''.

Answer 1

y=1+36x/(x+3)^2
y'=[36(x^2+6x+9)-36x(2x+6)]/(x+3)^4
=[324-36x^2]/(x+3)^4
y''=[-72(x+3)^4-4(324-36x^2)(x+3)^3
y=x^2+1/x
y'=2x-1/x^2
y''=2-2/x^3