Concept:The integrand is simplified by factoring x and using a substitution to reduce it to a standard logarithmic integral.Explanation:Given integral isI=∫x+xdx.Factor the denominator asx+x=x(1+x).So,I=∫x(1+x)dx.Let t=1+x.Thendxdt=2x1⇒xdx=2dt.Substituting into the integral,I=∫t2dt=2∫tdt.This givesI=2log∣t∣+c.Substitute back t=1+x:I=2log(1+x)+c.Answer:2log(1+x)+cHence, the correct option is D.