Question

Someone please help me solve this!!!

f^-1(3) when f(x)=2x+3/5

Answer 1

you function is:

I can just replace f(x) with a 3.

Answer 2

plug in 3 for f(x) (not f(3), but set f(x)=3 )

Answer 3

Okay, does this mean that it would be 2(3)+3/5??

Answer 4

no, it means that it is 3=2x+3/5

Answer 5

OHHHHHHH okay so now I do what?

Answer 6

soilve for x.

Answer 7

So solve 2x+3 first? then divide it by 5? is that right?

Answer 8

@SolomonZelman

Answer 9

is it y=(2x+3)/5 , it was that?

Answer 10

f(x)=2x+3/5

Answer 11

so 2x is NOT part of the fraction ?

Answer 12

Find the inverse of f(x) then evaluate it at 3.

Answer 13

No

Answer 14

it is easier to plug in 3 instead of y. Isn't it, Isaiah?

Answer 15

F(x)= 2x+3
----------
5

Answer 16

Oh, yes, so we are at: 3=(2x+3) / 5
multiply both sides by 5.

Answer 17

what do you get when you multiply both sides by 5, can you tell me?

Answer 18

So would it be.... 5x=2x+3???

Answer 19

@SolomonZelman I only know the traditional method.

Answer 20

If you need the f^(-1)(x) then do the traditional, but for this, I think you see why plugging in 3 for y, is still same as f^(-1)(3).

Answer 21

Okay, am i right with what i said for multiplying by 5?

Answer 22

@nicjohns
3=(2x+3)/5
3* 5 = 5* (2x+3)/5
15=2x+3

Answer 23

Okay and that is my final answer or i solve for x by one step equation?

Answer 24

So subtract 3 from both sides.... 12=2x. Divide by 2 on both sides and equal x=6????

Answer 25

you have to solve for x. isolate the x first by subtracting 3 from both sides, and then by dividing both sides by 2.

Answer 26

I just did that, and put it! x=6!!!!

Answer 27

yes, that is right!

Answer 28

Thank you so much!! I fi open another question so I can give you another medal, can you help me with one more???

Answer 29

I will see if I get more time to help you. yw:)