Question

Find the equation of the line normal to f(x)= x -2x^3 at x=1

Answer 1

$1 - 6 {x}^{2} = 1 - 6 = - 5 \\ slope \: of \: normal = \frac{1}{5}$
$f(1) = 1 - 2 = - 1 \\ (1. \: \: - 1)$
$y + 1 = 3(x - 1)$