(2x+8)(4x+9)=0

Solution for (2x+8)(4x+9)=0 equation:

(2x+8)(4x+9)=0

We multiply parentheses ..

(+8x^2+18x+32x+72)=0

We get rid of parentheses

8x^2+18x+32x+72=0

We add all the numbers together, and all the variables

8x^2+50x+72=0

a = 8; b = 50; c = +72;
Δ = b2-4ac
Δ = 502-4·8·72
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(50)-14}{2*8}=\frac{-64}{16}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(50)+14}{2*8}=\frac{-36}{16}
=-2+1/4
$