1.2x(x+5)=3.2x+8

Solution for 1.2x(x+5)=3.2x+8 equation:

1.2x(x+5)=3.2x+8

We move all terms to the left:

1.2x(x+5)-(3.2x+8)=0

We multiply parentheses

x^2+5x-(3.2x+8)=0

We get rid of parentheses

x^2+5x-3.2x-8=0

We add all the numbers together, and all the variables

x^2+1.8x-8=0

a = 1; b = 1.8; c = -8;
Δ = b2-4ac
Δ = 1.82-4·1·(-8)
Δ = 35.24
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{-(1.8)-\sqrt{35.24}}{2*1}=\frac{-1.8-\sqrt{35.24}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1.8)+\sqrt{35.24}}{2*1}=\frac{-1.8+\sqrt{35.24}}{2}
$