0=m^2-2m-15

Solution for 0=m^2-2m-15 equation:

0=m^2-2m-15

We move all terms to the left:

0-(m^2-2m-15)=0

We add all the numbers together, and all the variables

-(m^2-2m-15)=0

We get rid of parentheses

-m^2+2m+15=0

We add all the numbers together, and all the variables

-1m^2+2m+15=0

a = -1; b = 2; c = +15;
Δ = b2-4ac
Δ = 22-4·(-1)·15
Δ = 64
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{64}=8$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-8}{2*-1}=\frac{-10}{-2}
=+5
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+8}{2*-1}=\frac{6}{-2}
=-3
$