SOLUTION: Using Substition method find all solutions of the system of equations. x^2+y^2=25 , y=2x

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Question 372608: Using Substition method find all solutions of the system of equations.
x^2+y^2=25 , y=2x
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
The intersection of a line and a circle,
1.+x%5E2%2By%5E2=25
2.+y=2x
From eq. 2,
y%5E2=4x%5E2
Substitute into eq. 1,
x%5E2%2B4x%5E2=25
5x%5E2=25
x%5E2=5
x=0+%2B-+sqrt%285%29
Now solve for y
When x=sqrt%285%29, y=2x=2%2Asqrt%285%29
When x=-sqrt%285%29, y=-2%2Asqrt%285%29
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