0=0.7x^2-4.3x+5.5

Solution for 0=0.7x^2-4.3x+5.5 equation:

0=0.7x^2-4.3x+5.5

We move all terms to the left:

0-(0.7x^2-4.3x+5.5)=0

We add all the numbers together, and all the variables

-(0.7x^2-4.3x+5.5)=0

We get rid of parentheses

-0.7x^2+4.3x-5.5=0

a = -0.7; b = 4.3; c = -5.5;
Δ = b2-4ac
Δ = 4.32-4·(-0.7)·(-5.5)
Δ = 3.09
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{-(4.3)-\sqrt{3.09}}{2*-0.7}=\frac{-4.3-\sqrt{3.09}}{-1.4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4.3)+\sqrt{3.09}}{2*-0.7}=\frac{-4.3+\sqrt{3.09}}{-1.4}
$