5z2+20z=105

Solution for 5z2+20z=105 equation:

5z^2+20z=105

We move all terms to the left:

5z^2+20z-(105)=0

a = 5; b = 20; c = -105;
Δ = b2-4ac
Δ = 202-4·5·(-105)
Δ = 2500
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2500}=50$
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-50}{2*5}=\frac{-70}{10}
=-7
$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+50}{2*5}=\frac{30}{10}
=3
$