Question

what is the vertex of the graph of this function y=-(x+2)(x+4)?
A.) (3,-35)
B.) (-3,1)
C.) (-2,-4)
D.) (-3,-1)

Answer 1

The x intercepts are given to you within your sets of parenthesis. x + 2 = 0...x = -2.
x + 4 = 0...x = -4. So the points where the graph crosses the x axis are at -2 and -4. The x coordinate of the vertex is at x = -3, because the vertex is centered between the two x intercepts. Let's find y now...give me a sec to dwell on that one...

Answer 2

You have to complete the square on this to find the y coordinate. That works out like this:

Answer 3

do you mean (x+2)(x+4) because i got -x^2-6x-8

Answer 4

Hold on, let me finish something first ok? Don't multiply the negative into the polynomial; you just have to take it out again. so leave it out in front. It makes things easier.

Answer 5

x = -3

y=-((-3)+2)((-3)+4) = -(-1)(1) = 1

(-3,1)