(6a+6)(7a+5)=0

Solution for (6a+6)(7a+5)=0 equation:

(6a+6)(7a+5)=0

We multiply parentheses ..

(+42a^2+30a+42a+30)=0

We get rid of parentheses

42a^2+30a+42a+30=0

We add all the numbers together, and all the variables

42a^2+72a+30=0

a = 42; b = 72; c = +30;
Δ = b2-4ac
Δ = 722-4·42·30
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(72)-12}{2*42}=\frac{-84}{84}
=-1
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(72)+12}{2*42}=\frac{-60}{84}
=-5/7
$