121=81x^2

Solution for 121=81x^2 equation:

121=81x^2

We move all terms to the left:

121-(81x^2)=0

a = -81; b = 0; c = +121;
Δ = b2-4ac
Δ = 02-4·(-81)·121
Δ = 39204
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{39204}=198$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-198}{2*-81}=\frac{-198}{-162}
=1+2/9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+198}{2*-81}=\frac{198}{-162}
=-1+2/9
$