2x+x+(x+1)+x(x+15)=40

Solution for 2x+x+(x+1)+x(x+15)=40 equation:

2x+x+(x+1)+x(x+15)=40

We move all terms to the left:

2x+x+(x+1)+x(x+15)-(40)=0

We add all the numbers together, and all the variables

3x+(x+1)+x(x+15)-40=0

We multiply parentheses

x^2+3x+(x+1)+15x-40=0

We get rid of parentheses

x^2+3x+x+15x+1-40=0

We add all the numbers together, and all the variables

x^2+19x-39=0

a = 1; b = 19; c = -39;
Δ = b2-4ac
Δ = 192-4·1·(-39)
Δ = 517
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(19)-\sqrt{517}}{2*1}=\frac{-19-\sqrt{517}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(19)+\sqrt{517}}{2*1}=\frac{-19+\sqrt{517}}{2}
$