(6a+5)(3a-5)=0

Solution for (6a+5)(3a-5)=0 equation:

(6a+5)(3a-5)=0

We multiply parentheses ..

(+18a^2-30a+15a-25)=0

We get rid of parentheses

18a^2-30a+15a-25=0

We add all the numbers together, and all the variables

18a^2-15a-25=0

a = 18; b = -15; c = -25;
Δ = b2-4ac
Δ = -152-4·18·(-25)
Δ = 2025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2025}=45$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-45}{2*18}=\frac{-30}{36}
=-5/6
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+45}{2*18}=\frac{60}{36}
=1+2/3
$