Question

f-1(3) when f(x) = 2x plus 3, all over 5

Answer 1

@iambatman
@jim_thompson5910
@radar
@Zarkon
@jdoe0001

Answer 2

And please explain your steps

Answer 3

Alright, we want the inverse?

Answer 4

To find the inverse:

Replace f(x) with y
Switch x's and y's, so put x where y is and x where y is.
Solve for y
Replace y with f^-1(x)

Follow these steps, and see what you get, and once you have the inverse plug in the 3.

Answer 5

@iambatman i dont get it can you do it please?

Answer 6

You didn't even try it.

Answer 7

i did that before i dont get it

Answer 8

I'm not going to do this for you, I will help guide you but you need to do the heavy lifting.

Answer 9

Well can you show me your process?

Answer 10

I can then pin point where you went wrong.

Answer 11

like i replaced X with y

Answer 12

\[f(x) = \frac{ 2x+3 }{ 5 } \implies y = \frac{ 2x+3 }{ 5 }\]

Answer 13

yea that and i was stuck after that

Answer 14

Follow the steps I gave you, switch the x's and y's.

Answer 15

so x=2y+3/5

Answer 16

Yes :)

Answer 17

Now solve for y

Answer 18

then we multiply right?

Answer 19

Multiply what?

Answer 20

5 and 3?

Answer 21

Yes you multiply 5 but not 3, write it out, it will make much more sense.

Answer 22

so u muliply 5 with x and get 5x=2y+3

Answer 23

@iambatman

Answer 24

Yes

Answer 25

What you do to one side you must do to the other, remember this, so do same stuff on your right side on the left as well. That's algebra.

Answer 26

then we reverse the equality and get 2y+3=5x?

Answer 27

It doesn't matter, but that's fine.

Answer 28

Solve for y, what's your next step/

Answer 29

then isolate and get 2y=5x-3
then solve for y >?

Answer 30

so its
y=5x/2 - 3/2

Answer 31

Yes that's good

Answer 32

So i am done?

Answer 33

\[f^{-1}(x) = \frac{ 5x-3 }{ 2 }\] now quite, now plug in 3 for x and that will give you\[f^{-1}(3)\]

Answer 34

5(3)-3/2
15-3/2
12/2
6

Answer 35

Yup :)

Answer 36

Good job!

Answer 37

so am done :D thxxxx

Answer 38

Yes, now you're done

Answer 39

wait i got 6 for all of them

Answer 40

What do you mean?

Answer 41

Which of the following statements have the same result? Explain each step in solving each one.

f(1) when f(x) = 5x + 1
f-1(3) when f(x) = 2x plus 3, all over 5
3y - 7 = y + 5

Answer 42

i got 6 for all 3

Answer 43

That's fine

Answer 44

Explain your reasoning for all of them then :)

Answer 45

oh ok thx

Answer 46

wait you want to explain it now

Answer 47

Just to make sure we did the right problem, your question was \[f(x) = \frac{ 2x+3 }{ 5 }\] and not \[f(x) = 2x+\frac{ 3 }{ 5 }\]

Answer 48

The explaining is your job :)

Answer 49

ok thx