3m(3m-4)=20

Solution for 3m(3m-4)=20 equation:

3m(3m-4)=20

We move all terms to the left:

3m(3m-4)-(20)=0

We multiply parentheses

9m^2-12m-20=0

a = 9; b = -12; c = -20;
Δ = b2-4ac
Δ = -122-4·9·(-20)
Δ = 864
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{864}=\sqrt{144*6}=\sqrt{144}*\sqrt{6}=12\sqrt{6}$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-12\sqrt{6}}{2*9}=\frac{12-12\sqrt{6}}{18}
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+12\sqrt{6}}{2*9}=\frac{12+12\sqrt{6}}{18}
$