Question

Find all the values of x where the tangent line is horizontal.
2x^3+36x^2+192x+12

Answer 1

at x = -4 and -8
Take the derivative of the given equation to find rate of change of the graph.
f'(x) = 6x^2 + 72x + 192
At a horizontal tangent, f'(x) = 0, so set the equation equal to 0 and solve. Eventually you get x = -4 and -8