Question

A function f is such that f(x) = 15/ (2x+3) for 0 <=x<=6.
Find an expression for f'(x) and use your result to explain why f has an inverse.

Answer 1

\[\frac{ d f(x)}{ dx}\]

Answer 2

f'(x) = -30 (2x+3)^-2
How do you know whether f has an inverse or not. It's something go to do with the turning point.

Answer 3

u know how to differentiate ??

Answer 4

well the power which was before differentiation will come down

Answer 5

so -1 will come down and multiplied with 15

Answer 6

What? Lol.

Answer 7

I already differentiated.

Answer 8

\[\frac{ 15 }{ x+3 }=15*(x+3)^{-1}\]

Answer 9

Please check before you post.

Answer 10

-15*(x+3)^(-2)

Answer 11

yeah dear i already checked

Answer 12

got me now ??

Answer 13

Then? Explain why f has an inverse. I know how to differentiate. I just need to know why f has an inverse!!!!

Answer 14

a function should be one one ..u know abt it ??

Answer 15

Yes, but what does it got to do with the turning points?

Answer 16

hmm...we need to check for turning point because at that point inverse may exist or may not

Answer 17

It's so frustrating talking to you. You're not answering my question!

Answer 18

loll sorry..i was solving other Q and didnt recieve notificatrion...sorrrry dear

Answer 19

yeah tell me now i m

here

Answer 20

generally we dont check for turning point

Answer 21

if function is one one its ionverse will exist

Answer 22

No. I mean, why is it that no turning point = an inverse?

Answer 23

becozz at turning point inverse wont exist

Answer 24

turning point will not be in our domain

Answer 25

15/(2x+3)
here we can not take x=-3/2 because it will make denominator zero

Answer 26

and denominator should not be zero for a function

Answer 27

bcozz it will make value of function infinity

Answer 28

any more doubt ???

Answer 29

yes. i have doubt, as i dont understand what you're trying to say. haha. can you give me examples?

Answer 30

hmm
...like
f(x)=1/x

Answer 31

what will be its domain ??

Answer 32

like here we cant put x=0

Answer 33

bcozz 1/0= infinity

Answer 34

but value of function should be finite

Answer 35

so x=0 is turning point

Answer 36

omg, can give simpler one. Sorry. I still can't catch.

Answer 37

@amistre64

Answer 38

turning point is a fair way to assess an inverse.

for example: y=x^2 has a turning point, and has no inverse since:

(2)^2 = 4 and (-2)^2 = 4

an inverse would mean that if we wanted to know what makes y=4, there is more than one solution

Answer 39

alot to read over here, what is your question?