Question

Как решить $sqrt{9-x^2} =0$

Answer 1

$sqrt{9-x^2}=0|^2\ 9-x^2=0\-x^2=-9\x^2=9\ |{ {{x=3} atop {x=-3}} right.$
Ответ: $-3;3$

Answer 2

$sqrt{9-x^2} =0$
$(sqrt{9-x^2})^2 =0^2$
$9-x^2=0$
$3^2-x^2=0$
$(3-x)(3+x)=0$
$3-x=0$  или  $3+x=0$
$x_1=3$или  $x_2=-3$
Ответ:$-3;3.$