Question

LCD

Answer 1

First look at the number part.
3, 11, 7
What kind of numbers are 3, 11, and 7? Prime or not?

Answer 2

Since 3, 11, and 7 are all prime numbers, the LCD of the three numbers is their product,
3 * 11 * 7

Answer 3

Now look at the variable part.

Let's look at x first.
x, x^2, x
x^2 is a multiple of itself, x^2, and also a multiple of x, so for x, you need x^2 in the LCD.

Now look at y.
y, y, y^4
y^4 is a multiple of itself and a multiple of y, so for y you need y^4 in the LCD.

Now put together what you need for the number part, for x and for y, and there is your LCD.