y = 2^x
By increasing over each interval "twice as much" as the previous one, you should get points like (1, 2), (2, 4), and (3, 8). At x = 2, y = 4, which is twice as much as the value at x = 1, where y = 2 (2 x 2 = 4). This pattern is observable in the other following points.
If you make a chart of the values plotted by y = 2^x, they correlate, proving the answer.
x = 1, y = 2
x = 2, y = 4
x = 3, y = 8
x = 4, y = 16
x = 5, y = 32
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