I'm having a hard time with simultaneous quadratics. I've got this question and don't know how to start off on solving it. I know how to solve linear simultaneous equations and that's about it.
$$x^2 + y^2 = 25\\ y - 2x = 5$$
Ok, so I've managed to square the second equation and got
$$ (y-2x)(y-2x) = 25 = y^2 -4xy + 4x^2$$
I also find it hard to recognise when a pair of equations is a quadratic. How do I identify when it is a quadratic simultaneous equation?
plugging your second equation $$y=5+2x$$ in your first equation we get $$x^2+(5+2x)^2-25=0$$ expanding and factorizing we have to solve $$5x(x+4)=0$$ Can you solve the rest?