2x*x-x-10*2x-5=0

Solution for 2x*x-x-10*2x-5=0 equation:

2x*x-x-10*2x-5=0

We add all the numbers together, and all the variables

-1x+2x*x-10*2x-5=0

Wy multiply elements

2x^2-1x-20x-5=0

We add all the numbers together, and all the variables

2x^2-21x-5=0

a = 2; b = -21; c = -5;
Δ = b2-4ac
Δ = -212-4·2·(-5)
Δ = 481
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{-(-21)-\sqrt{481}}{2*2}=\frac{21-\sqrt{481}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-21)+\sqrt{481}}{2*2}=\frac{21+\sqrt{481}}{4}
$