5(a^2+6a-5)=0

Solution for 5(a^2+6a-5)=0 equation:

5(a^2+6a-5)=0

We multiply parentheses

5a^2+30a-25=0

a = 5; b = 30; c = -25;
Δ = b2-4ac
Δ = 302-4·5·(-25)
Δ = 1400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1400}=\sqrt{100*14}=\sqrt{100}*\sqrt{14}=10\sqrt{14}$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(30)-10\sqrt{14}}{2*5}=\frac{-30-10\sqrt{14}}{10}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(30)+10\sqrt{14}}{2*5}=\frac{-30+10\sqrt{14}}{10}
$