25x*25x-81=0

Solution for 25x*25x-81=0 equation:

25x*25x-81=0

Wy multiply elements

625x^2-81=0

a = 625; b = 0; c = -81;
Δ = b2-4ac
Δ = 02-4·625·(-81)
Δ = 202500
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{202500}=450$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-450}{2*625}=\frac{-450}{1250}
=-9/25
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+450}{2*625}=\frac{450}{1250}
=9/25
$