Differentiate the following functions with respect to x :
px2+qx+rax+b
Let y = px2+qx+rax+b
Differentiating y w.r.t. x, we get
dydx=(ax+b)ddx(px2+qx+r)−(px2+qx+r)ddx(ax+b)(ax+b)2 (By quotient formula)
(ax+b)(2px+q+0)−(px2+qx+r)(a×1+0)(ax+b)2
=(ax+b)(2px+q)−(px2+qx+r)a(ax+b)2
=(2apx2+apx+2bpx+bq)−(apx2+aqx+ra)(ax+b)2=2apx2+aqx+2bpx+bq−apx2−apx−ra(ax+b)2
⇒ dydx=apx2+2bpx+bq−ra(ax+b)2