SOLUTION: please please please what is logx81=4

Question 2172: please please please what is
logx81=4
Found 2 solutions by vms, khwang:
Answer by vms(2) (Show Source): You can put this solution on YOUR website!
logx81=4
we know logxa=k if a= x^k
that means ...
if 'a' can be written as k th power of x then we say k is logarithm of a to base x.
as we see 3 = 3^1
9=3^2
27=3^3
81=3^4
which shows 81 can be got as 4th power of 3. so, logx81=4 implies x=3
Answer by khwang(438) (Show Source): You can put this solution on YOUR website!
Use loga b = 1/logb a,we have
logx 81= 4 converts to
1/log81 x = 4,
or log81 x = 1/4,
Hence, x = (81)^1/4 by definition of logarithm.
So, x = (81)^1/4 = (3^4)^(1/4) = 3^1 = 3.
Or use logx 81= log 81/log x = 4, (common logarithm:base 10)
So,log x = (log 81)/4,
x = 10^((log 81)/4) = 10^((log 3^4)/4) = 10^(4(log 3)/4)
= 10^(log 3) = 3
Kenny

RELATED QUESTIONS
Please (answered by malakumar_kos@yahoo.com)
PLEASE (answered by richwmiller)
What value of x will make the following equation true? logx81 = 4 (answered by jsmallt9)
What value of x will make the following equation true? logx81 = 4 (answered by Alan3354)
What value of x will make the following equation true? logx81 = 4 (answered by richard1234)
please help what is 16/4 radical... (answered by checkley71)
what is (-4-8i) (3+i) please solve... (answered by Fombitz)
what is 2(x - 4) =22? can you please... (answered by Flannery,richard1234)
What is 9 choosing 4? (9C4) please show all... (answered by MathLover1,checkley79)