9x^2+9x^2=25

Solution for 9x^2+9x^2=25 equation:

9x^2+9x^2=25

We move all terms to the left:

9x^2+9x^2-(25)=0

We add all the numbers together, and all the variables

18x^2-25=0

a = 18; b = 0; c = -25;
Δ = b2-4ac
Δ = 02-4·18·(-25)
Δ = 1800
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1800}=\sqrt{900*2}=\sqrt{900}*\sqrt{2}=30\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-30\sqrt{2}}{2*18}=\frac{0-30\sqrt{2}}{36}
=-\frac{30\sqrt{2}}{36}
=-\frac{5\sqrt{2}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+30\sqrt{2}}{2*18}=\frac{0+30\sqrt{2}}{36}
=\frac{30\sqrt{2}}{36}
=\frac{5\sqrt{2}}{6}
$