128=y*y+y

Solution for 128=y*y+y equation:

128=y*y+y

We move all terms to the left:

128-(y*y+y)=0

We add all the numbers together, and all the variables

-(+y+y*y)+128=0

We get rid of parentheses

-y-y*y+128=0

We add all the numbers together, and all the variables

-1y-y*y+128=0

Wy multiply elements

-1y^2-1y+128=0

a = -1; b = -1; c = +128;
Δ = b2-4ac
Δ = -12-4·(-1)·128
Δ = 513
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{513}=\sqrt{9*57}=\sqrt{9}*\sqrt{57}=3\sqrt{57}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-3\sqrt{57}}{2*-1}=\frac{1-3\sqrt{57}}{-2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+3\sqrt{57}}{2*-1}=\frac{1+3\sqrt{57}}{-2}
$