Question

find an equation of the normal line to f(x)=5x^2-7 at x=-1

Answer 1

Do you know calculus? If so, differentiate f(x) to get the function for the slope of the tangent to the curve at x. Then take the negative reciprocal of that to get the slope of the normal (in other words, the perpendicular to the tangent). Evaluate that at x = -1. Also find the value of y = f(-1) so you have a known point to run your normal line through using the point-slope formula: \[y -y_0 = m(x-x_0)\]