(1.2x-2)(8x+5.6)=0

Solution for (1.2x-2)(8x+5.6)=0 equation:

(1.2x-2)(8x+5.6)=0

We multiply parentheses ..

(+8x^2+5.6x-16x-11.2)=0

We get rid of parentheses

8x^2+5.6x-16x-11.2=0

We add all the numbers together, and all the variables

8x^2-10.4x-11.2=0

a = 8; b = -10.4; c = -11.2;
Δ = b2-4ac
Δ = -10.42-4·8·(-11.2)
Δ = 466.56
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{-(-10.4)-\sqrt{466.56}}{2*8}=\frac{10.4-\sqrt{466.56}}{16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10.4)+\sqrt{466.56}}{2*8}=\frac{10.4+\sqrt{466.56}}{16}
$