x^2-4.2x+2.9=0

Solution for x^2-4.2x+2.9=0 equation:

x^2-4.2x+2.9=0

a = 1; b = -4.2; c = +2.9;
Δ = b2-4ac
Δ = -4.22-4·1·2.9
Δ = 6.04
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{-(-4.2)-\sqrt{6.04}}{2*1}=\frac{4.2-\sqrt{6.04}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4.2)+\sqrt{6.04}}{2*1}=\frac{4.2+\sqrt{6.04}}{2}
$