16Hit1600
Advanced MathVery hardWhere exponential overtakes linear

Advanced Math practice question

The functions f and g are defined by f(x) = 3x + 10 and g(x) = 2ˣ. For which of the following is g(x) greater than f(x) for the first time as x increases through the positive integers?

  1. A. 5Correct
  2. B. 4
  3. C. 6
  4. D. 3

Answer: A. 5

At x = 4, g = 16 < f = 22. At x = 5, g = 32 > f = 25. So x = 5 is the first.

Why the other answers are wrong

B. 4
At x = 4, 16 < 22.
C. 6
g is already ahead at x = 5.
D. 3
At x = 3, 8 < 19.

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