x*x=81/100

Solution for x*x=81/100 equation:

x*x=81/100

We move all terms to the left:

x*x-(81/100)=0

We add all the numbers together, and all the variables

x*x-(+81/100)=0

Wy multiply elements

x^2-(+81/100)=0

We get rid of parentheses

x^2-81/100=0

We multiply all the terms by the denominator


x^2*100-81=0

Wy multiply elements

100x^2-81=0

a = 100; b = 0; c = -81;
Δ = b2-4ac
Δ = 02-4·100·(-81)
Δ = 32400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{32400}=180$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-180}{2*100}=\frac{-180}{200}
=-9/10
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+180}{2*100}=\frac{180}{200}
=9/10
$