3.48: Normal gradient and normal equation

Find the coordinates of the point on the curve $y = (1 + 3x)^{\frac{1}{2}}$ where the gradient of the normal is $-\dfrac{8}{3}$.

Find the equation of the normal to the curve $y = (1 + 3x)^{\frac{1}{2}}$ at the point $(8,\ 5)$ in the form $y = mx + c$.