Question

What is x^2+( 5√2-x)^2= 5√2^2

Answer 1

$x^2+( 5\sqrt2-x)^2= (5\sqrt2)^2\\ x^2+50-10\sqrt2x+x^2=50\\ 2x^2-10\sqrt2x=0\\ x^2-5\sqrt2x=0\\ x(x-5\sqrt2)=0\\ x=0 \vee x=5\sqrt2$