4.9x^2-3.9x-64=0

Solution for 4.9x^2-3.9x-64=0 equation:

4.9x^2-3.9x-64=0

a = 4.9; b = -3.9; c = -64;
Δ = b2-4ac
Δ = -3.92-4·4.9·(-64)
Δ = 1269.61
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{-(-3.9)-\sqrt{1269.61}}{2*4.9}=\frac{3.9-\sqrt{1269.61}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3.9)+\sqrt{1269.61}}{2*4.9}=\frac{3.9+\sqrt{1269.61}}{9.8}
$