5m^2-21m-54=0

Solution for 5m^2-21m-54=0 equation:

5m^2-21m-54=0

a = 5; b = -21; c = -54;
Δ = b2-4ac
Δ = -212-4·5·(-54)
Δ = 1521
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1521}=39$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-21)-39}{2*5}=\frac{-18}{10}
=-1+4/5
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-21)+39}{2*5}=\frac{60}{10}
=6
$