(7x+14)(2x-6)=0

Solution for (7x+14)(2x-6)=0 equation:

(7x+14)(2x-6)=0

We multiply parentheses ..

(+14x^2-42x+28x-84)=0

We get rid of parentheses

14x^2-42x+28x-84=0

We add all the numbers together, and all the variables

14x^2-14x-84=0

a = 14; b = -14; c = -84;
Δ = b2-4ac
Δ = -142-4·14·(-84)
Δ = 4900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4900}=70$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-14)-70}{2*14}=\frac{-56}{28}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14)+70}{2*14}=\frac{84}{28}
=3
$