SOLUTION: I have tried completing the square and quad formula for the following question and I am stuck.. y=2xsquared-8 I have to graph this but do not know how?.. Obviously y=-8 but how

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: I have tried completing the square and quad formula for the following question and I am stuck.. y=2xsquared-8 I have to graph this but do not know how?.. Obviously y=-8 but how       Log On


   

Question 350939: I have tried completing the square and quad formula for the following question and I am stuck..
y=2xsquared-8
I have to graph this but do not know how?..
Obviously y=-8 but how do I find x?
Thanks for any input since I seem to be having a brain fart...
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
y=2x%5E2-8 Start with the given equation.


0=2x%5E2-8 Plug in y=0


8=2x%5E2 Add 8 to both sides.


8%2F2=x%5E2 Divide both sides by 2.


4=x%5E2 Reduce.


x%5E2=4 Flip the equation.


x=%22%22%2B-sqrt%284%29 Take the square root of both sides.


x=sqrt%284%29 or x=-sqrt%284%29 Break up the plus/minus.


x=2 or x=-2 Take the square root of 4 to get 2.


So when y=0, x=2 or x=-2


Put another way, we have the points (2,0) and (-2,0)


So the x-intercepts are (2,0) and (-2,0)


If you need more help, email me at jim_thompson5910@hotmail.com

Also, feel free to check out my tutoring website

Jim