Question

Given the function f(x) = log3(x + 4), find the value of f−1(3).

f−1(3) = 7
f−1(3) = 12
f−1(3) = 23
f−1(3) = 31

Answer 1

let log 3(x+4) =3 to find x

Answer 2

\(f(x) =\color{red}{a}\), then \(f^{-1}\color{red}{(a)}= x\)
hence if you let \(log_3(x+4)=\color{red}{3}\) then \(f^{-1}\color{red}{(3)}=x\) so, just solve for x

Answer 3

so we make (x+4)^log3=3 and we subtract 4 from both sides? @Loser66

Answer 4

@Hero

Answer 5

@phi

Answer 6

@i_suck_at_school

Answer 7

@quickstudent

Answer 8

I justHAD that question

Answer 9

hang on\

Answer 10

are you taking alg2 ?

Answer 11

calculus

Answer 12

can you help me solving this? please

Answer 13

I'm not at 2 yet. I'm still studying algebra 1.

Answer 14

@Preetha @mathrulezz @hartnn

Answer 15

is it a test

Answer 16

check this out and see if it helps

Answer 17

http://www.math.utah.edu/~wortman/1050-text-l.pdf

Answer 18

http://www.ltcconline.net/greenl/courses/154/keys/pExam2W11Key.htm

Answer 19

i appreciate it @i_suck_at_school but idk it didn't answer my question , i'm so frustrated

Answer 20

@Hotchellerae21

Answer 21

@Luigi0210 @Directrix @sammixboo @Miracrown @Legends @OpTicRebekah @Data_LG2 @Shadowgirl15 @IrishBoy123 @kourtneyceciliax

Answer 22

f (x) = log3 (x −2)
find f (11)
y = log3(11− 2)
y = log3 (9)
to find log3 [ (9)
ask what power of 3 is 9
log3(9) = 2]
y = log3(9)
y = 2
(11 ,2 )

Answer 23

not you problem just example

Answer 24

i assume that f-1(3) means the inverse. this has been presented badly and may have led to confusion.

IF it is true that you are trying to find an inverse, then you are trying to solve:

log3(x + 4) = 3, ie what x gives 3 as the answer

assuming base e (as opposed to 10 or any other poss base), this means that:

3(x+4) = e^(3)
solve from here for x.

assuming base 10, you want to solve:

3(x+4) = 10^3

hope this helps.

Answer 25

it is c i am sorry 4 giving answer

Answer 26

too late but here's how i do it:
let f(x)=y
solve for the inverse...
remember inverse is switching x and y
\(\sf f(x) = log_3(x + 4)\\y=log_3(x + 4)\\\color{red}{x}=log_3(\color{red}{y} + 4)\)
Arrange the equation in terms of \(\sf \color{red}{y}\)
then plug the give value of x, which is 3
you'll end up the same thing as they got :)

Answer 27

@DoShKa_SyRiA

Answer 28

Thank you so much i understand it now @Data_LG2

Answer 29

@i_suck_at_school i appreciate your help a lot man

Answer 30

@i_suck_at_school how is it c i thought it was A.

Answer 31

i am a girl

Answer 32

oh i'm sorry you have a guy picture so that's why i assumed so

Answer 33

@i_suck_at_school

Answer 34

its ight

Answer 35

but why did you say it's c?

Answer 36

isn't the answer A?

Answer 37

so we plug in 3 in x .. 3= log3(y+4) correct?

Answer 38

@Data_LG2

Answer 39

https://answers.yahoo.com/question/index?qid=20150112074052AAckwtA

Answer 40

3 = log3(x + 4)
x + 4 = 3^3 = 27 ... i don't understand this part
x = 23

f-1(3) = 23.

Answer 41

@i_suck_at_school @Data_LG2

Answer 42

http://www.purplemath.com/modules/logrules3.htm

Answer 43

scroll to bottom and ask away

Answer 44

@DoShKa_SyRiA

Answer 45

g2g c is right

Answer 46

just sayin