4.9x^2+4x-20=0

Solution for 4.9x^2+4x-20=0 equation:

4.9x^2+4x-20=0

a = 4.9; b = 4; c = -20;
Δ = b2-4ac
Δ = 42-4·4.9·(-20)
Δ = 408
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{408}=\sqrt{4*102}=\sqrt{4}*\sqrt{102}=2\sqrt{102}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-2\sqrt{102}}{2*4.9}=\frac{-4-2\sqrt{102}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+2\sqrt{102}}{2*4.9}=\frac{-4+2\sqrt{102}}{9.8}
$