SOLUTION: Quadratic Relations 39) The vertex of a parabola is (-2,-4). One x-intercept is 7. What is the other x-intercept? (PLEASE) Thank you very muchhhhhhhhhhhh

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Quadratic Relations 39) The vertex of a parabola is (-2,-4). One x-intercept is 7. What is the other x-intercept? (PLEASE) Thank you very muchhhhhhhhhhhh      Log On


   

Question 178078: Quadratic Relations
39) The vertex of a parabola is (-2,-4). One x-intercept is 7. What is the other x-intercept? (PLEASE)
Thank you very muchhhhhhhhhhhh
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
I know that the x co-ordinate of the vertex is midway between the
2 x-intercepts, so I can use the formula
x%5Bv%5D+=+%28x%5B1%5D+%2B+x%5B2%5D%29%2F2
I'm told that the vertex is at (-2,-4), so x%5Bv%5D+=+-2,
and also given is x%5B1%5D+=+7
-2+=+%287+%2B+x%5B2%5D%29%2F2
-4+=+7+%2B+x%5B2%5D
x%5B2%5D+=+-11
The other x-intercept is at x = -11