X=4-40y+100y^2

Solution for X=4-40y+100y^2 equation:

X=4-40X+100X^2

We move all terms to the left:

X-(4-40X+100X^2)=0

We get rid of parentheses

-100X^2+40X+X-4=0

We add all the numbers together, and all the variables

-100X^2+41X-4=0

a = -100; b = 41; c = -4;
Δ = b2-4ac
Δ = 412-4·(-100)·(-4)
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(41)-9}{2*-100}=\frac{-50}{-200}
=1/4
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(41)+9}{2*-100}=\frac{-32}{-200}
=4/25
$