3^(n + 2) = 81
n + 2 = 4
n = 2
PS
Use brackets to clarify question.
What you have in fact typed means:-
(3^n) + 2 = 81
i.e. a completely different question.
2007-10-17 22:05:00
·
answer #1
·
answered by Como 7
·
0⤊
0⤋
Hello,
3^(n+2) = 81 so 3^(n+2) = 3^4 so since the bases the exponents must be equal then n+2 = 4 so n = 2.
Hope This Helps!
2007-10-16 21:36:11
·
answer #2
·
answered by CipherMan 5
·
1⤊
0⤋
n = 2
4th root of 81 = 3
3^4 = 81
2007-10-16 21:35:42
·
answer #3
·
answered by Anonymous
·
0⤊
0⤋
3^(n+2)=81 dont get confuse with 3^n+2=81
Your answer suggest we have 3^(n+2)=81 situation.
so it means 3 times how many it self will be 81?
3 = 3
3*3=9
3*3*3=27
3*3*3*3=81
Now you get 3^4 = 81
4=n+2
n=2
2007-10-16 21:37:53
·
answer #4
·
answered by john_lu66 4
·
1⤊
0⤋
oh, you mean 3^(n+2)=81 xD
To do this, you'll need to know some logarithm laws:
Log2(2^x)=x
Log3(3^x)=x
Log base 'x', x to the power of something always equals something
Sooo, you could do:
Log3(3^n+2)=Log3(81)
n+2=4
n=2
Another law is that Log(x)^y=yLog(x)
Sooo, you could also do Log(3^(n+2))=log(81)
(n+2)(Log(3))=Log(81)
N+2=Log(81)/Log(3)
n=(Log(81)/Log(3))-2
n=2
The last way is to just think of exponentials
3^(n+2)=81, 81=3^4
3^(n+2)=3^4, get rid of the bases, since they are the same
n+2=4
n=2
2007-10-16 21:39:15
·
answer #5
·
answered by Chaotic_Shadow 3
·
0⤊
0⤋
I assume you meant
3^(n+2)=81 not 3^n +2 =81
3^(n+2) = 3^n (3^2) =81
3^n = 9
3^2 =9 , hence n =2
To avoid any confusion, please use parentheses to make it easy for all
2007-10-16 21:39:39
·
answer #6
·
answered by Any day 6
·
0⤊
0⤋
n does not equal 2
3^2 +2= 11
get to 3^n=79
now do ln3^n=ln79
ln is the natural log on calculator
n=ln79/ln3
n=3.977242834
2007-10-16 21:37:06
·
answer #7
·
answered by Anonymous
·
0⤊
0⤋
3^n+2 = 81
3^n = 79
ln(3^n) = ln(79)
(n)ln(3) = ln(79)
n = ln(79)/ln(3)
or is it 3^(n+2)?
if this is the case, you know that 3^4 = 81. so if you set up the equation like this:
n+2 = 4
n=2.
2007-10-16 21:36:13
·
answer #8
·
answered by seaniquanzo 2
·
1⤊
0⤋
3x3=9x3=27x3=81
this is 3^4
s0 n=2
2007-10-16 21:36:02
·
answer #9
·
answered by science teacher 7
·
0⤊
0⤋