SOLUTION: (8) Question: Solve the system: x^2 +y^2=20 x^2-2y^2=8 (THIS PROBLEM IS WRITTEN EXACTLY AS IT APPEARS!) (A) (1, sqrt19) (1, -sqrt19) (-1, sqrt19), (-1, -sqrt19) (B)(4,2) (4

Algebra ->  College  -> Linear Algebra -> SOLUTION: (8) Question: Solve the system: x^2 +y^2=20 x^2-2y^2=8 (THIS PROBLEM IS WRITTEN EXACTLY AS IT APPEARS!) (A) (1, sqrt19) (1, -sqrt19) (-1, sqrt19), (-1, -sqrt19) (B)(4,2) (4      Log On


   

Question 30461: (8) Question:
Solve the system:
x^2 +y^2=20
x^2-2y^2=8
(THIS PROBLEM IS WRITTEN EXACTLY AS IT APPEARS!)
(A) (1, sqrt19) (1, -sqrt19) (-1, sqrt19), (-1, -sqrt19)
(B)(4,2) (4, -2)
(C) 04, 2) (-4, -2)
(D) 4, 2) (4, -2) (-4, 2) (-4, -2)
Please be specific as to which letter answer is correct
Thanks
Answer by mukhopadhyay(490) About Me  (Show Source):
You can put this solution on YOUR website!
x^2 +y^2=20 => y^2=20-x^2
x^2-2y^2=8 => x^2 -2(20-x^2)=8 => 3x^2=48 => x^2=16 => x= 4 or x= -4
y^2=20-x^2
=>y^2=20-16 => y^2=4 => y=2 or y=-2
Correct answer is D