3x(x+4)-5x=26

Solution for 3x(x+4)-5x=26 equation:

3x(x+4)-5x=26

We move all terms to the left:

3x(x+4)-5x-(26)=0

We add all the numbers together, and all the variables

-5x+3x(x+4)-26=0

We multiply parentheses

3x^2-5x+12x-26=0

We add all the numbers together, and all the variables

3x^2+7x-26=0

a = 3; b = 7; c = -26;
Δ = b2-4ac
Δ = 72-4·3·(-26)
Δ = 361
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{361}=19$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-19}{2*3}=\frac{-26}{6}
=-4+1/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+19}{2*3}=\frac{12}{6}
=2
$