y=(x^2+1)ln(x^2+1),求dy
问题描述：
y=(x^2+1)ln(x^2+1),求dy
答
dy=ln(x²+1)d(x²+1)+(x²+1)dln(x²+1)=ln(x²+1)*2xdx+(x²+1)*1/(x²+1)*d(x²+1)=2xln(x²+1)dx+2xdx=[2xln(x²+1)+2x]dx
y=(x^2+1)ln(x^2+1),求dy
dy=ln(x²+1)d(x²+1)+(x²+1)dln(x²+1)=ln(x²+1)*2xdx+(x²+1)*1/(x²+1)*d(x²+1)=2xln(x²+1)dx+2xdx=[2xln(x²+1)+2x]dx