(2x+3)(x+1)=28

Solution for (2x+3)(x+1)=28 equation:

(2x+3)(x+1)=28

We move all terms to the left:

(2x+3)(x+1)-(28)=0

We multiply parentheses ..

(+2x^2+2x+3x+3)-28=0

We get rid of parentheses

2x^2+2x+3x+3-28=0

We add all the numbers together, and all the variables

2x^2+5x-25=0

a = 2; b = 5; c = -25;
Δ = b2-4ac
Δ = 52-4·2·(-25)
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-15}{2*2}=\frac{-20}{4}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+15}{2*2}=\frac{10}{4}
=2+1/2
$