Question

What is the vertex of g(x) = –3x2 + 18x + 2?

(3, –25)
(–3, –25)
(3, 29)
(–3, 29)

Answer 1

The vertex would be D) (-3, 29)

Explanation:

To find the vertex , start by find the x-value. For this we can use the equation below.

x = -b/2a

In which a is the coefficient of x^2 and b is the coefficient of x.

x = -b/2a

x = -(18)/2(-3)

x = -18/-6

x = 3

Now that we have x, we find y by plugging 3 in for each x.

g(x) = -3x^2 + 18x + 2

g(x) = -3(3)^2 + 18(3) + 2

g(x) = -3(9) + 18(3) + 2

g(x) = -27 + 54 + 2

g(x) = 29

Answer 2

C

Explanation:

You start by making it into a function in standard form.

Then you factor the "a" term (in this case -3) out of the first two numbers.

Third, you must form a perfect square trinomial.

Fourth, you have to write the trinomial as a binomial squared.

Lastly you have to write the function in vertex form.