4x^2+20x+15=-3x

Solution for 4x^2+20x+15=-3x equation:

4x^2+20x+15=-3x

We move all terms to the left:

4x^2+20x+15-(-3x)=0

We get rid of parentheses

4x^2+20x+3x+15=0

We add all the numbers together, and all the variables

4x^2+23x+15=0

a = 4; b = 23; c = +15;
Δ = b2-4ac
Δ = 232-4·4·15
Δ = 289
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{289}=17$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(23)-17}{2*4}=\frac{-40}{8}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(23)+17}{2*4}=\frac{-6}{8}
=-3/4
$