30=u^2-u

Solution for 30=u^2-u equation:

30=u^2-u

We move all terms to the left:

30-(u^2-u)=0

We get rid of parentheses

-u^2+u+30=0

We add all the numbers together, and all the variables

-1u^2+u+30=0

a = -1; b = 1; c = +30;
Δ = b2-4ac
Δ = 12-4·(-1)·30
Δ = 121
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{121}=11$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-11}{2*-1}=\frac{-12}{-2}
=+6
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+11}{2*-1}=\frac{10}{-2}
=-5
$