Answer
The solutions are -3 and 5.
Work Step by Step
$x^{2}$-2x=15
$x^{2}$-2x-15=15-15
$x^{2}$-2x-15=0
$x^{2}$+3x-5x-15=0
x(x+3)-5(x+3)=0
(x-5)(x+3)=0
x-5=0 or x+3=0
x-5+5=0+5 or x+3-3=0-3
x=5 or x=-3
The solutions are -3 and 5.
Check
Let x=-3 Let
$x^{2}$-2x=15
$(-3)^{2}$-2(-3)=15
9+6=15
15=15
Let x=5
$x^{2}$-2x=15
$5^{2}$-2*5=15
25-10=15
15=15