u2=2.5

Solution for u2=2.5 equation:

u2=2.5

We move all terms to the left:

u2-(2.5)=0

We add all the numbers together, and all the variables

u^2-2.5=0

a = 1; b = 0; c = -2.5;
Δ = b2-4ac
Δ = 02-4·1·(-2.5)
Δ = 10
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{10}}{2*1}=\frac{0-\sqrt{10}}{2}
=-\frac{\sqrt{}}{2}
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{10}}{2*1}=\frac{0+\sqrt{10}}{2}
=\frac{\sqrt{}}{2}
$