25x^2-49=15

Solution for 25x^2-49=15 equation:

25x^2-49=15

We move all terms to the left:

25x^2-49-(15)=0

We add all the numbers together, and all the variables

25x^2-64=0

a = 25; b = 0; c = -64;
Δ = b2-4ac
Δ = 02-4·25·(-64)
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-80}{2*25}=\frac{-80}{50}
=-1+3/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+80}{2*25}=\frac{80}{50}
=1+3/5
$