# SOLUTION: Find the exact solutions of the system of equations x^2+2y^2=18 and x=2y Thanks

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 Question 43860: Find the exact solutions of the system of equations x^2+2y^2=18 and x=2y ThanksAnswer by adamchapman(301)   (Show Source): You can put this solution on YOUR website!you know that y=2x, so replace y in the longer equation with 2x: Now x^2+2y^2=18 Becomes x^2+2(2x)^2=18 This can be simplified: x^2 + 2(4x^2) = 18 x^2 + 8x^2 = 18 9x^2=18 Now divide both side by 9: x^2=9 So x=3 or x=-3 Recalling that y=2x; y=6 or y=-6 This can be written in the form of coordinates on a graph, like this: "The solutions are (3,6) and (-3,-6)" I hope this helps. If you have any other problems please don't hesitate to contact me at adam.chapman@student.manchester.ac.uk