Question

Which table represents a linear function?

Answer 1

 first one ( 3, 7, 11, 15) because it is going by 4

Answer 2

Linear means that the y values go up in a fixed increment, k.
In the first one, you see that 3+4=7, 7+4=11, and so on, so you can immediately tell that it's linear.

The second one goes 3+5=8, then 8+7=15, then 15+6=21, which aren't the same numbers.

The third increases and decreases, so it's not linear.

The fourth goes 3+6=9, then 9+18=27, which you can immediately tell is not linear.

Therefore, the only linear table would be the first one.