SOLUTION: Hi I just get confused with the numbers raised and how to finish off this question. I have that 18x^2=162 for the problem 9x^2+y^2=81 and 9x^2-y^2=81. What do I do next? thank you.

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: Hi I just get confused with the numbers raised and how to finish off this question. I have that 18x^2=162 for the problem 9x^2+y^2=81 and 9x^2-y^2=81. What do I do next? thank you.      Log On


   



Question 1028395: Hi I just get confused with the numbers raised and how to finish off this question. I have that 18x^2=162 for the problem 9x^2+y^2=81 and 9x^2-y^2=81. What do I do next? thank you.
Answer by FrankM(1040) About Me  (Show Source):
You can put this solution on YOUR website!
18x%5E2=162
If you don't 'see' that both 18 and 162 are multiples of 9, or that 162 is a multiple of 18, you might see that they are both even. So both can divide by 2.
9x%5E2=81
Now, the numbers should be easier. As we know 9*9 is 81, so divide both side by 9.
x%5E2=9

x=3 or x=-3