SOLUTION: Could you please help with the following problem. It needs to be solved using the elimination method. The answer that I calculated is not what the book shows. Thanks. x^2+y^2=16

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: Could you please help with the following problem. It needs to be solved using the elimination method. The answer that I calculated is not what the book shows. Thanks. x^2+y^2=16      Log On


   

Question 134936This question is from textbook algebra 2
: Could you please help with the following problem. It needs to be solved using the elimination method. The answer that I calculated is not what the book shows. Thanks.
x^2+y^2=16
4x^2-9y^2=36
The answer must be in square root format (different form what the book asks for) This question is from textbook algebra 2

Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
Given : x%5E2%2By%5E2=16
4x%5E2-9y%5E2=36+
9x%5E2%2B9y%5E2=144
Add these two
13x%5E2++++=+180
+x%5E2+=+%28180%2F13%29
+x+=+sqrt%28180%2F13%29
+x+=+%28sqrt%28180%29%2Asqrt%2813%29%29%2F13%29
+x+=+%28sqrt%2836%29%2Asqrt%285%29%2Asqrt%2813%29%29%2F13%29
+x+=+%286%2Asqrt%285%29%2Asqrt%2813%29%29%2F13%29
+x+=+%286%2Asqrt%2865%29%29%2F13%29