Evaluate a logarithmic function

Evaluate http://curriculum.kcdistancelearning...t4_Exam_25.gif

Please show work :)
I got that the answer is 4 because 7^log₇ = 1

I would suggest that you start with the definition of the logarthm: If then . Here 'a' is 7 and 'b' is , therefore from the right hand side of the definition . Hence c = 4, and .

You are absolutely right. You can also proceed like this. Let c = 7^(ln4 to the base 7) taking log on both sides we get (lnc to the base 7) = (ln4 to the base 7) and that gices c = 4. Hence 7^(ln4 to the base 7)= 4