10u*u=40

Solution for 10u*u=40 equation:

10u*u=40

We move all terms to the left:

10u*u-(40)=0

Wy multiply elements

10u^2-40=0

a = 10; b = 0; c = -40;
Δ = b2-4ac
Δ = 02-4·10·(-40)
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-40}{2*10}=\frac{-40}{20}
=-2
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+40}{2*10}=\frac{40}{20}
=2
$