When the x-value has increased by 1 unit, the y-value has multiplied by 3, so we expect a function of the form (something)×(3^x). The last choice has that.
... f(x) = 4(3)^x
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You can always evaluate the offered choices at the given points to see which of them works. The second point (2, 36) will tell you the fastest.
4·3^-2 = 4/9 ≠ 36 . . . . . you can tell at this point you don't want -x as the exponent
3·4^-2 = 3/16 ≠ 36
3·4^2 = 48 ≠ 36
4·3^2 = 36 = 36 . . . . this is the one you want
