Q. Which of the following is equivalent to log7(a)⋅logb(7) ?Choose 1 answer:(A) log(7)(B) log(7a)(C) loga(b)(D) logb(a)
Recognize change of base formula: Recognize the use of the change of base formula.The expression log7(a)⋅logb(7) suggests the use of the change of base formula, which is logc(a)=logd(c)logd(a) for any positive numbers a, c, and d (where a,c=1).
Apply change of base formula to log: Apply the change of base formula to logb(7).We can rewrite logb(7) using the change of base formula with a new base, which we'll choose as 'a'. This gives us logb(7)=loga(b)loga(7).
Substitute expression from Step 2: Substitute the expression from Step 2 into the original expression.Now we replace logb(7) in the original expression with the result from Step 2, which gives us log7(a)⋅(loga(b)loga(7)).
Simplify the expression: Simplify the expression.We notice that log7(a) and loga(7) are inverses of each other, meaning their product is 1. So, the expression simplifies to loga(b)1.
Recognize simplified expression as a logarithm: Recognize the simplified expression as a logarithm.The expression loga(b)1 is the same as logb(a) by the definition of the reciprocal of a logarithm.
Match simplified expression to answer choices: Match the simplified expression to the answer choices.The expression logb(a) corresponds to answer choice (D).