Question

Juliana has created the function f(x) = the quantity of 3x plus 2, divided by 4 to represent the cost of texting on her current plan, where x represents the number of texts. Juliana discovers that using the inverse function to solve for x = 24, she can predict how many texts she can use for $24. Explain to Juliana how to accomplish this, using complete sentences

Answer 1

@myininaya @hba

Answer 2

If you can just explain how to solve a function I can write the sentences myself I'm just terrible at functions

Answer 3

Ok, so explain in symbols what f(x) is?

Answer 4

f(x) is the number of her text, right?

Answer 5

No, it says this:
f(x) = the quantity of 3x plus 2, divided by 4 to represent the cost of texting on her current plan, where x represents the number of texts

It says that f(x) is cost of the texting whereas x is number of texts.
I'm just asking you to explain using mathematical symbols what f(x) is?

Answer 6

isn't it always f(x) = so it's what everything equals?

Answer 7

So can you please give it to me in symbols please?
I'm just asking you to translate the quantity of 3x plus 2, divided by 4.
This is what f(x) is according to your paragraph.

Answer 8

f(x)= \[\frac{ 3x +2 }{ 4 }\] I don't really understand what you're asking i'm sorry...

Answer 9

I was asking for what f(x) was which is the thing you just stated.

The equal sign means is.

Answer 10

Now they are asking for the inverse function.
This means solve for x basically.

Answer 11

you have y=(3x+2)/4

Answer 12

Okay..so what's first

Answer 13

Well how do you undo division by 4?

Answer 14

I really don't know I'm sorry..wouldn't you do something with distributive property I think it's called?

Answer 15

\[y=\frac{3x+2}{4}\]
\[y=\frac{3x+2}{4 \text{ <--- Do you see this 4 underneath here? } }\]

Answer 16

Yes, I see the 4

Answer 17

Like we need to get that 4 out of the denominator?
Since that 4 is in the denominator we recognize this as division by 4.

To undo division by 4, we multiply by 4.
Whatever we do to one side we do to the other.

Because 1/4 * 4=1
Correct?

Answer 18

Yes, correct.

Answer 19

Ok then what do you get after multiplying both sides by 4?

Answer 20

Do you need to do distributive property? Where you would do 3x * 4 and 2*4 ?

Answer 21

If so then it would be (12x + 8)

Answer 22

Well I'm asking you to multiply 4 on sides....like this
4y=4(3x+2)/4
The whole reason we multiplied by 4 was to undo that division by 4.

So now we have
4y=(3x+2)

or just simply

4y=3x+2

(parenthesis not needed)

Remember your objective is to get x.

You are almost there.

Answer 23

@myininnaya I know this was a long time ago but I am also stuck on this problem and I need some help, would you help me finish the problem???

Answer 24

f(x)=3x+2/4