0.4x^2-0.8x=1.7

Solution for 0.4x^2-0.8x=1.7 equation:

0.4x^2-0.8x=1.7

We move all terms to the left:

0.4x^2-0.8x-(1.7)=0

We add all the numbers together, and all the variables

0.4x^2-0.8x-1.7=0

a = 0.4; b = -0.8; c = -1.7;
Δ = b2-4ac
Δ = -0.82-4·0.4·(-1.7)
Δ = 3.36
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{-(-0.8)-\sqrt{3.36}}{2*0.4}=\frac{0.8-\sqrt{3.36}}{0.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.8)+\sqrt{3.36}}{2*0.4}=\frac{0.8+\sqrt{3.36}}{0.8}
$