X^2-42x+0.8=0

Solution for X^2-42x+0.8=0 equation:

X^2-42X+0.8=0

a = 1; b = -42; c = +0.8;
Δ = b2-4ac
Δ = -422-4·1·0.8
Δ = 1760.8
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{-(-42)-\sqrt{1760.8}}{2*1}=\frac{42-\sqrt{1760.8}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-42)+\sqrt{1760.8}}{2*1}=\frac{42+\sqrt{1760.8}}{2}
$