Question

найдите корень уравнения X^2-21=24

Answer 1

$x^2-21=24 \\x^2-21-24 =0\\x^2-45=0\\(x-\sqrt{45})(x+\sqrt{45})=0\\x-\sqrt{45}=0\ \ \ \ \ \ \ \ \ x+\sqrt{45}=0\\x=\sqrt{45}\ \ \ \ \ \ \ \ \ \ \ \ \ \ x=-\sqrt{45}\\x=3\sqrt{5}\ \ \ \ \ \ \ \ \ \ \ \ \ \ x=-3\sqrt{5}$

Ответ:

x=3√5, x=-3√5