Question

Решите уравнение
x^2-4x -1 = 3
x-1 9-x^2

Answer 1

$x^2-4x-1=3 \ x^2-4x-4=0 \ D=16+16=32=(4 sqrt{2})^2 \ x_1= frac{4+4 sqrt{2} }{2}(:2)=2+2 sqrt{2} \ x_2=2-2 sqrt{2}$

$(x-1)(9-x^2)=0 \ \ x-1=0 \ x=1 \ \ 9-x^2=0 \ x^2=9 \ x=pm3$
ОТВЕТ: x=1; x=-3; x=3