X^2-4.9x+2.8=0

Solution for X^2-4.9x+2.8=0 equation:

X^2-4.9X+2.8=0

a = 1; b = -4.9; c = +2.8;
Δ = b2-4ac
Δ = -4.92-4·1·2.8
Δ = 12.81
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{-(-4.9)-\sqrt{12.81}}{2*1}=\frac{4.9-\sqrt{12.81}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4.9)+\sqrt{12.81}}{2*1}=\frac{4.9+\sqrt{12.81}}{2}
$