Question

怎么求导数啊?二阶导数

Answer 1

f'(x)=(2+x)/(2-x)*[(2-x)/(2+x)]'

=(2+x)/(2-x)*[(-(2+x)-(2-x))/(2+x)^2]

=(2+x)/(2-x)*[(-4)/(2+x)^2]

=-4/(4-x^2)

f''(x)=-4*[1/(4-x^2)]'

=-4*(-(4-x^2)')/(4-x^2)^2

=-8x/(4-x^2)^2

f''(1)=-8/9