(7x+6)(x+3)=0

Solution for (7x+6)(x+3)=0 equation:

(7x+6)(x+3)=0

We multiply parentheses ..

(+7x^2+21x+6x+18)=0

We get rid of parentheses

7x^2+21x+6x+18=0

We add all the numbers together, and all the variables

7x^2+27x+18=0

a = 7; b = 27; c = +18;
Δ = b2-4ac
Δ = 272-4·7·18
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(27)-15}{2*7}=\frac{-42}{14}
=-3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(27)+15}{2*7}=\frac{-12}{14}
=-6/7
$