Q. Evaluate.log991Write your answer in simplest form.
Understand the problem: Understand the problem.We need to find the value of the logarithm of 91 with base 9. The logarithm logbase(b)(a) answers the question: "To what power must we raise b to obtain a?" In this case, we are looking for the power to which 9 must be raised to get 91.
Apply the definition: Apply the definition of a logarithm.We know that 9 to the power of −1 equals 91 (since 91 is the reciprocal of 9, and the reciprocal of a number is that number to the power of −1). Therefore, log9(91) is asking for the exponent that makes 9 equal to 91.
Calculate the logarithm: Calculate the logarithm.Since 9−1=91, by the definition of logarithms, log9(91)=−1.