(5x+10)(3x+12)=0

Solution for (5x+10)(3x+12)=0 equation:

(5x+10)(3x+12)=0

We multiply parentheses ..

(+15x^2+60x+30x+120)=0

We get rid of parentheses

15x^2+60x+30x+120=0

We add all the numbers together, and all the variables

15x^2+90x+120=0

a = 15; b = 90; c = +120;
Δ = b2-4ac
Δ = 902-4·15·120
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(90)-30}{2*15}=\frac{-120}{30}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(90)+30}{2*15}=\frac{-60}{30}
=-2
$