Question

Write a rule for the function:

x -2, -1, 0, 1, 2
y 1/147, 1/21, 1/3, 7/3, 49/3

Answer 1

y = 1/3(7)^x.

Explanation:

Note that the y values increase by a factor 7:

1/21 = 1/147 * 7, 1/3 = 1/21 * 7, and so on.

So the rule is:

y = 1/3(7)^x.

Check:

When x = 0, y = 1/3 * (7)^0 = 1/3

When x = 2 , y = 1/3(7)^2 = 49/3.

When x = -2 , y = 1/3(7)^-2 = 1/3 * 1/7^2 = 1/147.