## Calculus (3rd Edition)

$$\frac{d}{dx}((ax+b)(abx^2+1))=a(abx^2+1)+2abx(ax+b).$$
By using the product rule, we have $$\frac{d}{dx}((ax+b)(abx^2+1))=a(abx^2+1)+2abx(ax+b).$$