# Evaluate a logarithmic function

• Jan 31st 2013, 07:29 AM
dzomberg
Evaluate a logarithmic function
Evaluate http://curriculum.kcdistancelearning...t4_Exam_25.gif

Please show work :)
I got that the answer is 4 because 7log7 = 1
• Jan 31st 2013, 07:43 AM
ebaines
Re: Evaluate a logarithmic function
I would suggest that you start with the definition of the logarthm: If $a^b = c$ then $\log_a c = b$. Here 'a' is 7 and 'b' is $\log_7 4$, therefore from the right hand side of the definition $\log_7 c = b = log_7 4$. Hence c = 4, and $7^{\log_7 4} = 4$.
• Jan 31st 2013, 09:00 PM
ibdutt
Re: Evaluate a logarithmic function
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