(X-6)(7x+28)=0

Solution for (X-6)(7x+28)=0 equation:

(X-6)(7X+28)=0

We multiply parentheses ..

(+7X^2+28X-42X-168)=0

We get rid of parentheses

7X^2+28X-42X-168=0

We add all the numbers together, and all the variables

7X^2-14X-168=0

a = 7; b = -14; c = -168;
Δ = b2-4ac
Δ = -142-4·7·(-168)
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*7}=\frac{-56}{14}
=-4
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14)+70}{2*7}=\frac{84}{14}
=6
$