Question

What are the solution(s) to the quadratic equation 40 − x2 = 0?

Answer 1

$40-x^2=0\ \ \ |add\ x^2\ to\ both\ sides\\\\x^2=40\iff x=\pm\sqrt{40}\\\\x=-\sqrt{4\cdot10}\ or\ x=\sqrt{4\cdot10}\\\\x=-\sqrt4\cdot\sqrt{10}\ or\ x=\sqrt4\cdot\sqrt{10}\\\\\boxed{x=-2\sqrt{10}\ or\ x=2\sqrt{10}}$

Answer 2

$40-x^2=0\\ x^2=40\\ x=-\sqrt{40} \vee x=\sqrt{40}\\ x=-2\sqrt{10} \vee x=2\sqrt{10}$