Associate
Hi there,
I have a simultaneous equation question that has been driving me crazy and I just can't see what I am doing wrong.
x^2 - 2y^2 = 8
x + 2y = 8
So, here is what I did:
I squared the 2nd equation to get
x^2 + 2y^2 = 64
I then added the new equation and the x^2 - 2y^2 = 8 equation to get
2x^2 = 72
I then divided both sides by 2 to get
x^2 = 36
and then square rooted x to get
x = 6
However, this doesn't work for both equations and the answers in the back of the book say x = 4, y = 2 OR x = -20, y = 14.
Could someone please show me where I am going wrong
Cheers
I have a simultaneous equation question that has been driving me crazy and I just can't see what I am doing wrong.
x^2 - 2y^2 = 8
x + 2y = 8
So, here is what I did:
I squared the 2nd equation to get
x^2 + 2y^2 = 64
I then added the new equation and the x^2 - 2y^2 = 8 equation to get
2x^2 = 72
I then divided both sides by 2 to get
x^2 = 36
and then square rooted x to get
x = 6
However, this doesn't work for both equations and the answers in the back of the book say x = 4, y = 2 OR x = -20, y = 14.
Could someone please show me where I am going wrong
Cheers