Question

Find all values of x on the graph of f(x) = 2x3 + 6x2 + 7 at which there is a horizontal tangent line.

Answer 1

the equation is not correct, u have to write like

ax'3+bx'2+cx+d

Answer 2

x=-2 and x=0

Explanation:

So I know it isn't x=-3 and x=0. So my guess is that it is x=0 and x=-2 and heres why.

First, I find the derivative of f(x)=2x^3+6x^2+7 which is 6x^2+12x

Then, I plugged in all the values of x's I had and I found out that you get 0 for -2 and 0 when you plug them in

So, in conclusion I believe the answer to be x=-2 and x=0