Question Detail

MTH 102 MTH 102 Past Questions Objective Question

Question

Evaluate lim x→0 (ax - 1) / x
Options
A log x
B log a
Correct Answer
C 1
D ∞
Correct Answer

Option B is the correct answer.

Detailed Explanation

This is a standard limit that defines the derivative of the function f(x) = a^x at x = 0.The definition of the derivative f'(c) is limx→c (f(x) - f(c)) / (x - c).Here, f(x) = a^x and c = 0.So, limx→0 (a^x - a^0) / (x - 0) = f'(0).We know that the derivative d/dx (a^x) = a^x ln a (or a^x log_e a).Therefore, f'(0) = a^0 ln a = 1 * ln a = ln a.In higher mathematics, 'log a' often refers to the natural logarithm (ln a) when the base is not specified.

Hint

Recall the definition of the derivative from first principles or use L'Hopital's rule. The derivative of a^x is a^x ln a.

Question Info