-3x(4-x)=2x+5

Solution for -3x(4-x)=2x+5 equation:

-3x(4-x)=2x+5

We move all terms to the left:

-3x(4-x)-(2x+5)=0

We add all the numbers together, and all the variables

-3x(-1x+4)-(2x+5)=0

We multiply parentheses

3x^2-12x-(2x+5)=0

We get rid of parentheses

3x^2-12x-2x-5=0

We add all the numbers together, and all the variables

3x^2-14x-5=0

a = 3; b = -14; c = -5;
Δ = b2-4ac
Δ = -142-4·3·(-5)
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-14)-16}{2*3}=\frac{-2}{6}
=-1/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14)+16}{2*3}=\frac{30}{6}
=5
$