2+25.5*x-4.9*x^2=0

Solution for 2+25.5*x-4.9*x^2=0 equation:

2+25.5x-4.9x^2=0

a = -4.9; b = 25.5; c = +2;
Δ = b2-4ac
Δ = 25.52-4·(-4.9)·2
Δ = 689.45
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{-(25.5)-\sqrt{689.45}}{2*-4.9}=\frac{-25.5-\sqrt{689.45}}{-9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(25.5)+\sqrt{689.45}}{2*-4.9}=\frac{-25.5+\sqrt{689.45}}{-9.8}
$