Question

If $x+y=b$ and $xy=c$, find $x^2+y^2$

Answer 1

$x+y=b$ or $(x+y{)}^2=b^2$
or $x^2+y^2+2xy=b^2$
or $x^2+y^2+2c=b^2$
or $x^2+y^2=b^2-2c$