64=m^2+3m

Solution for 64=m^2+3m equation:

64=m^2+3m

We move all terms to the left:

64-(m^2+3m)=0

We get rid of parentheses

-m^2-3m+64=0

We add all the numbers together, and all the variables

-1m^2-3m+64=0

a = -1; b = -3; c = +64;
Δ = b2-4ac
Δ = -32-4·(-1)·64
Δ = 265
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-\sqrt{265}}{2*-1}=\frac{3-\sqrt{265}}{-2}
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+\sqrt{265}}{2*-1}=\frac{3+\sqrt{265}}{-2}
$