Question

-0,2х^2+45=0 .......

Answer 1

-0.2x^2+45=0
-0.2x^2=-45
x^2=-45:(-0.2)
x^2=225
x=ñ225
x=±15

$left { {{x=15} atop {x=-15}} right.$

x∈(-15;15)