X(3+X)+2x=75

Solution for X(3+X)+2x=75 equation:

X(3+X)+2X=75

We move all terms to the left:

X(3+X)+2X-(75)=0

We add all the numbers together, and all the variables

X(X+3)+2X-75=0

We add all the numbers together, and all the variables

2X+X(X+3)-75=0

We multiply parentheses

X^2+2X+3X-75=0

We add all the numbers together, and all the variables

X^2+5X-75=0

a = 1; b = 5; c = -75;
Δ = b2-4ac
Δ = 52-4·1·(-75)
Δ = 325
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{325}=\sqrt{25*13}=\sqrt{25}*\sqrt{13}=5\sqrt{13}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-5\sqrt{13}}{2*1}=\frac{-5-5\sqrt{13}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+5\sqrt{13}}{2*1}=\frac{-5+5\sqrt{13}}{2}
$