(2x+8)(7x+9)=0

Solution for (2x+8)(7x+9)=0 equation:

(2x+8)(7x+9)=0

We multiply parentheses ..

(+14x^2+18x+56x+72)=0

We get rid of parentheses

14x^2+18x+56x+72=0

We add all the numbers together, and all the variables

14x^2+74x+72=0

a = 14; b = 74; c = +72;
Δ = b2-4ac
Δ = 742-4·14·72
Δ = 1444
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1444}=38$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(74)-38}{2*14}=\frac{-112}{28}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(74)+38}{2*14}=\frac{-36}{28}
=-1+2/7
$