What is the vertex of y=2(x +3)^2 -8x y=2(x+3)28x?

1 Answer
Dec 21, 2015

The vertex is (-1,16)(1,16).

Explanation:

In order to know, we will develop first, it will make the next calculus easier.

y = 2x^2 + 12x + 18 - 8x = 2x^2 + 4x + 18y=2x2+12x+188x=2x2+4x+18. The coefficient of x^2x2 is positive so we know the vertex is a minimum. This vertex will be the zero of the derivative of this trinomial. So we need its derivative.

f(x) = 2x^2 + 4x + 18f(x)=2x2+4x+18 so f'(x) = 4x + 4 = 4(x+1). This derivative is zero for x = -1 so the vertex is at the point (-1,f(-1)) = (-1,16)