25r^2-9=27

Solution for 25r^2-9=27 equation:

25r^2-9=27

We move all terms to the left:

25r^2-9-(27)=0

We add all the numbers together, and all the variables

25r^2-36=0

a = 25; b = 0; c = -36;
Δ = b2-4ac
Δ = 02-4·25·(-36)
Δ = 3600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3600}=60$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-60}{2*25}=\frac{-60}{50}
=-1+1/5
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+60}{2*25}=\frac{60}{50}
=1+1/5
$