(3a+2)(a-7)=0

Solution for (3a+2)(a-7)=0 equation:

(3a+2)(a-7)=0

We multiply parentheses ..

(+3a^2-21a+2a-14)=0

We get rid of parentheses

3a^2-21a+2a-14=0

We add all the numbers together, and all the variables

3a^2-19a-14=0

a = 3; b = -19; c = -14;
Δ = b2-4ac
Δ = -192-4·3·(-14)
Δ = 529
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{529}=23$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-19)-23}{2*3}=\frac{-4}{6}
=-2/3
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-19)+23}{2*3}=\frac{42}{6}
=7
$