81=7.3y^2

Solution for 81=7.3y^2 equation:

81=7.3y^2

We move all terms to the left:

81-(7.3y^2)=0

We get rid of parentheses

-7.3y^2+81=0

a = -7.3; b = 0; c = +81;
Δ = b2-4ac
Δ = 02-4·(-7.3)·81
Δ = 2365.2
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{2365.2}}{2*-7.3}=\frac{0-\sqrt{2365.2}}{-14.6}
=-\frac{\sqrt{}}{-14.6}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{2365.2}}{2*-7.3}=\frac{0+\sqrt{2365.2}}{-14.6}
=\frac{\sqrt{}}{-14.6}
$