2.5^2+6.5^2=c^2

Solution for 2.5^2+6.5^2=c^2 equation:

2.5^2+6.5^2=c^2

We move all terms to the left:

2.5^2+6.5^2-(c^2)=0

We add all the numbers together, and all the variables

-1c^2+48.5=0

a = -1; b = 0; c = +48.5;
Δ = b2-4ac
Δ = 02-4·(-1)·48.5
Δ = 194
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{194}}{2*-1}=\frac{0-\sqrt{194}}{-2}
=-\frac{\sqrt{}}{-2}
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{194}}{2*-1}=\frac{0+\sqrt{194}}{-2}
=\frac{\sqrt{}}{-2}
$