another log question

G

Guest

Guest
I am terrible at logs

log5 1/5 =

a. -3
b. -2
c. -1
d. 1
e. 2 is this it?
f. 3
g. 4
h. none of these
 
G'day,

Recall that
\(\displaystyle y = \log_5{(1/5)}\)

Means
\(\displaystyle 5^y = \frac{1}{5}\)

Can you see what \(\displaystyle y\) must be?
 
Hello, adam40g!

\(\displaystyle log_5\left(\frac{1}{5}\right)\ =\)

\(\displaystyle a)\;-3\qquad\qquad b)\;-2\qquad\qquad c)\;-1\qquad\qquad d)\;1\qquad\qquad e)\;2\)

\(\displaystyle f)\;3\qquad\qquad g)\;4\qquad\qquad h)\;\text{none of these}\)
Let .\(\displaystyle \log_5\left(\frac{1}{5}\right) \:= \:x\)

Then we have: . \(\displaystyle 5^x \;= \;\frac{1}{5}\)

. . . . . . . . . .or: . \(\displaystyle 5^x \;= \;5^{-1}\)

. . . . . . Hence: . . \(\displaystyle x \;= \;-1\) *


Therefore: . \(\displaystyle \log_5\left(\frac{1}{5}\right) \;= \;-1\) . . . answer (c)

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

If we have two equal exponential expressions: .\(\displaystyle b^x\ =\ b^y\)

. . and their bases are equal, then the exponents are equal: .\(\displaystyle x\ =\ y\)
 
Top