1. ## sim. equ.

x^2+y^2=20
2y-x=0

simultaneous equations- started but doing something wrong.

2. Originally Posted by lra11
x^2+y^2=20
2y-x=0
From the second equation $x=2y.$

Substitute that into the first equation, then solve for $y,$ after that you'll get the values for $x.$

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A related problem has been posted not long ago, let me find it and I'll edit my post. (Here is it. It's the same procedure.)

3. From the second equation $x=2y$.
Plug x in the first equation and you'll get
$x^2+4x^2=20\Leftrightarrow 5x^2=20\Leftrightarrow x^2=4\Leftrightarrow x=\pm 2$.
Then $y=\pm 1$.