Answer:
D. 2x²
Explanation:
Ok, so the first thing to do is remember the first number in parentheses is x, and the second number is y.
You're trying to figure out which expression turns x into y in each set.
Just by plugging in the numbers into each expression I found that the answer is 2x².
I'll prove this starting with (1, 2).
1² = 1
2 x 1 = 2
So, y = 2x²!
Next, (2, 8).
2² = 4
2 x 4 = 8
So, y = 2x²!
I'm not going to demonstrate with the other two but I hope you understand. Just plug the values of x and y into the equation and see which is correct.