Question

Solve the equation by the method of completing the squares:
$x^2+12x-45=0$

Answer 1

$x^2+12x-45=0$

$\Rightarrow x^2+12x+36-45-36=0$

$x^2+12x+36=81$

${(x+6)}^2=81$

$(x+6)=\pm \sqrt{81}$

$x=-6\pm 9$

$x=-6+9,x=-6-9$

$\Rightarrow x=3,x=-15.$

Hence, the answer is $3,-15.$