(6x+3)(7x-14)=0

Solution for (6x+3)(7x-14)=0 equation:

(6x+3)(7x-14)=0

We multiply parentheses ..

(+42x^2-84x+21x-42)=0

We get rid of parentheses

42x^2-84x+21x-42=0

We add all the numbers together, and all the variables

42x^2-63x-42=0

a = 42; b = -63; c = -42;
Δ = b2-4ac
Δ = -632-4·42·(-42)
Δ = 11025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{11025}=105$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-63)-105}{2*42}=\frac{-42}{84}
=-1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-63)+105}{2*42}=\frac{168}{84}
=2
$