10x^2-1=99

Solution for 10x^2-1=99 equation:

10x^2-1=99

We move all terms to the left:

10x^2-1-(99)=0

We add all the numbers together, and all the variables

10x^2-100=0

a = 10; b = 0; c = -100;
Δ = b2-4ac
Δ = 02-4·10·(-100)
Δ = 4000
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:

$\sqrt{\Delta}=\sqrt{4000}=\sqrt{400*10}=\sqrt{400}*\sqrt{10}=20\sqrt{10}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-20\sqrt{10}}{2*10}=\frac{0-20\sqrt{10}}{20}
=-\frac{20\sqrt{10}}{20}
=-\sqrt{10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+20\sqrt{10}}{2*10}=\frac{0+20\sqrt{10}}{20}
=\frac{20\sqrt{10}}{20}
=\sqrt{10}
$