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

Solution for 4(x+2)(x+1)=15 equation:

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

We move all terms to the left:

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

We multiply parentheses ..

4(+x^2+x+2x+2)-15=0

We multiply parentheses

4x^2+4x+8x+8-15=0

We add all the numbers together, and all the variables

4x^2+12x-7=0

a = 4; b = 12; c = -7;
Δ = b2-4ac
Δ = 122-4·4·(-7)
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{-(12)-16}{2*4}=\frac{-28}{8}
=-3+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(12)+16}{2*4}=\frac{4}{8}
=1/2
$