((x-1)(x+1))/2=10,5

Solution for ((x-1)(x+1))/2=10,5 equation:

((x-1)(x+1))/2=10.5

We move all terms to the left:

((x-1)(x+1))/2-(10.5)=0

We add all the numbers together, and all the variables

((x-1)(x+1))/2-10.5=0

We use the square of the difference formula

x^2-1-10.5=0

We add all the numbers together, and all the variables

x^2-11.5=0

a = 1; b = 0; c = -11.5;
Δ = b2-4ac
Δ = 02-4·1·(-11.5)
Δ = 46
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{-(0)-\sqrt{46}}{2*1}=\frac{0-\sqrt{46}}{2}
=-\frac{\sqrt{}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{46}}{2*1}=\frac{0+\sqrt{46}}{2}
=\frac{\sqrt{}}{2}
$