The equation is not typed properly, and it is difficult to understand. But it is clear that you are trying to determine the value of y that makes your equation undefined.
An fraction is undefined if it's denominator is zero, that is if it's of the form a/0.
The value that makes a fraction undefined is the value that makes the denominator vanish. The value that makes its denominator equal to zero.
Example:
1. (x - 3)/(y - 5) is undefined if
y - 5 = 0
Or y = 5
2. (3x² + 4xy + 6)/(x + 2)(y + 6)
If x + 2 = 0, or y + 6 = 0
That is if x = -2, or y = -6
You can use this idea to find the value of y that makes your equation undefined.
