Equation of the line normal to the graph of y=x3+3 x2+7 x-1 at the point where x=-1, is

Question

Equation of the line normal to the graph of y=x3+3 x2+7 x-1 at the point where x=-1, is (A) 4 x+y=-10 (B) 4 x-y=2 (C) 2 x-y=4 (D) x+4 y=-25

Tardigrade Admin · Accepted Answer

y(-1)=-6, y prime(-1)=3 x2+6 x+.7|x=-1=4, the slope of the normal is (-1/4) and an equation for the normal is (y+6)=(-1/4)(x+1) ⇒ x+4 y=-25

Q. Equation of the line normal to the graph of $y = x^{3} + 3 x^{2} + 7 x - 1$ at the point where $x = - 1$ , is