SOLUTION: Give the axis of symmetry and the x-intercepts: Y = 2x^2 - 8x - 42

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Question 49925: Give the axis of symmetry and the x-intercepts:
Y = 2x^2 - 8x - 42
Answer by rapaljer(4671) About Me  (Show Source):
You can put this solution on YOUR website!
The line of symnmetry will be at the vertex. The vertex for y = ax^2 + bx +c will always be at x=%28-b%29%2F%282a%29+

In this case a=2 and b = -8, so vertex is at x=8%2F%282%2A2%29=2

To find the x-intercepts, let y = 0, and
solve the equation 0=2x^2 - 8x - 42 by factoring if possible.

2(x^2 - 4x -21)=0
2(x-7)(x+3)=0
x= 7 ; x = -3

This is a parabola that opens upward. You didn't ask to graph it, but it should look like this:
graph+%28300%2C300%2C-10%2C10%2C-50%2C46%2C+2x%5E2-8x-42%29+

R^2 at SCC