a^2+2.6^2=3.9^2

Solution for a^2+2.6^2=3.9^2 equation:

a^2+2.6^2=3.9^2

We move all terms to the left:

a^2+2.6^2-(3.9^2)=0

We add all the numbers together, and all the variables

a^2-8.45=0

a = 1; b = 0; c = -8.45;
Δ = b2-4ac
Δ = 02-4·1·(-8.45)
Δ = 33.8
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{33.8}}{2*1}=\frac{0-\sqrt{33.8}}{2}
=-\frac{\sqrt{}}{2}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{33.8}}{2*1}=\frac{0+\sqrt{33.8}}{2}
=\frac{\sqrt{}}{2}
$