-4.9x^2-98x-100=0

Solution for -4.9x^2-98x-100=0 equation:

-4.9x^2-98x-100=0

a = -4.9; b = -98; c = -100;
Δ = b2-4ac
Δ = -982-4·(-4.9)·(-100)
Δ = 7644
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:

$\sqrt{\Delta}=\sqrt{7644}=\sqrt{196*39}=\sqrt{196}*\sqrt{39}=14\sqrt{39}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-98)-14\sqrt{39}}{2*-4.9}=\frac{98-14\sqrt{39}}{-9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-98)+14\sqrt{39}}{2*-4.9}=\frac{98+14\sqrt{39}}{-9.8}
$