4.9x^2-1.25x-1=0

Solution for 4.9x^2-1.25x-1=0 equation:

4.9x^2-1.25x-1=0

a = 4.9; b = -1.25; c = -1;
Δ = b2-4ac
Δ = -1.252-4·4.9·(-1)
Δ = 21.1625
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{-(-1.25)-\sqrt{21.1625}}{2*4.9}=\frac{1.25-\sqrt{21.1625}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.25)+\sqrt{21.1625}}{2*4.9}=\frac{1.25+\sqrt{21.1625}}{9.8}
$