Mathematics. Solve: 0.00009 = 9^c
What's the value of the power c?
2006-09-26 23:07:30 · 4 answers · asked by Anonymous in Education & Reference ➔ Primary & Secondary Education
Mathematics. Solve: 0.00009 = 9^c
What's the value of the power c?
This question appeared in a examination paper whereby the students do not need to learn log. =|
2006-09-26 23:24:54 · update #1
Your variable is in an exponent, so you should automatically think of taking a logarithm. Logs are how you get variables out of exponents.
log(0.00009) = log(9^c)
By one of the log rules, this turns into:
log(0.00009) = c*log(9)
Divide by log(9) to get:
log(0.00009)/log(9) = c
Plug that into a calculator, and you get c = -4.2398. That's your answer.
Note that it doesn't matter what base logs you use... you can use regular base 10 logs, or natural logs ln, or base 9 logs, whatever pleases you. All will give the same answer. Logs are neat that way.
2006-09-26 23:20:04 · answer #1 · answered by Bramblyspam 7 · 0⤊ 0⤋
c<1
2006-09-26 23:09:26 · answer #2 · answered by vani3624 3 · 0⤊ 1⤋
9^-5
2006-09-26 23:10:19 · answer #3 · answered by Alex 3 · 0⤊ 0⤋
log( base 9)o.oooo9
2006-09-26 23:13:32 · answer #4 · answered by I want to delete my answers account 3 · 0⤊ 0⤋