y=1/(x^2+1)(x^2+1+x)
y=(x^2+1)^(-1)(x^2+1+x)
dy/dx=(x^2+1)^(-1)(2x+1)+(x^2+1+x)(-1)(x^2+1)^(-2)(2x)
dy/dx=(x^2+1)^(-2)[(x^2+1)(2x+1)+(x^2+1+x)(-2x)]
y=1/(x^2+1)(x^2+1+x)
y=(x^2+1)^(-1)(x^2+1+x)
dy/dx=(x^2+1)^(-1)(2x+1)+(x^2+1+x)(-1)(x^2+1)^(-2)(2x)
dy/dx=(x^2+1)^(-2)[(x^2+1)(2x+1)+(x^2+1+x)(-2x)]