Nonlinear System Solution Strategies

[oray]

Homework Statement

Solve the nonlinear system.

x^2-2y^2=16
x^2+y^2=25

Homework Equations

n/a?

The Attempt at a Solution

ive tried subtracting 1 equation from the other...
(x^2-2y^2+9)=25
-(x^2+y^2)=25
-3y^2+9=25
-3y^2=16
y^2=-16/3
y=root of -16/3...
im not even sure if that part is right, also, i don't know where to go after that.
help?

 

[Tedjn]

You've forgotten to subtract the RHS as well.

 

[oray]

huh? I am confused? what is the RHS? i really am confused on where to start in general.

 

[slider142]

huh? I am confused? what is the RHS? i really am confused on where to start in general.

When you subtracted one equation from the other, you subtracted the left-hand side (LHS) of your equations, but did not do the same for the right-hand side (RHS), which was 25-25 = 0.

 

[oray]

okay...
(x^2-2y^2+9)=25
-(x^2+y^2)=25
-3y^2+9=0
-3y^2=-9
y^2=-3
y=null?

 

[Dick]

You have -3y^2=(-9). That doesn't give you y^2=(-3), does it? I think I remember once dividing -9 by -3 and I didn't get -3.

 

[oray]

awesome. figured it out. thanks for all the help people :)