Final answer:
The domain of the expression (y^2 + 1) / (y^2 - 2y) is all real numbers except for y = 0 and y = 2 because the denominator cannot be zero.
Step-by-step explanation:
The domain of the expression (y^2 + 1) / (y^2 - 2y) can be found by looking at the denominator of the fraction. The denominator cannot be zero because division by zero is undefined in mathematics. Therefore, we must solve the inequality y^2 - 2y ≠ 0 to find the values that y cannot take. This simplifies to y(y - 2) ≠ 0, which gives us y ≠ 0 and y ≠ 2. Therefore, the domain of the expression is all real numbers except for y = 0 and y = 2.