(X-4)(3x+10)=0

Solution for (X-4)(3x+10)=0 equation:

(X-4)(3X+10)=0

We multiply parentheses ..

(+3X^2+10X-12X-40)=0

We get rid of parentheses

3X^2+10X-12X-40=0

We add all the numbers together, and all the variables

3X^2-2X-40=0

a = 3; b = -2; c = -40;
Δ = b2-4ac
Δ = -22-4·3·(-40)
Δ = 484
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{484}=22$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-22}{2*3}=\frac{-20}{6}
=-3+1/3
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+22}{2*3}=\frac{24}{6}
=4
$