Question

f(x) = 8 - 2x. Find f^-1(y)

Answer 1

f(x) = 8 - 2x
y = 2x - 8
x = 2y - 8
x +8 = 2y
f^-1(x) = x + 8 / 2
correct?

Answer 2

it looks weird that I have f^-1(x) = x + 8 / 2

Answer 3

@tHe_FiZiCx99 go ahead fizi :)

Answer 4

._. I'm watching anime ;_;

Answer 5

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)

Alright with that said, lets do it in steps:

f(x) = 8-2x
y = 8-2x
x=8-2y
x-8=2y
(x-8)/2 = y
f^-1(x) = (x-8)/2

Answer 6

I think you mean to say f^-1(x)

And no, you went wrong in the signs.

f(x) = -2x + 8
y = -2x + 8

Switch the x for the y

x = -2y + 8, now solve for Y

(x - 8) = -2y
/-2 /-2

\(\ \sf \Large \dfrac{(x - 8)}{-2} = y \)

Now change y back to\(\ \sf \Large f^{-1}(x)\)

Answer 7

I switched it because 8 - 2x was different than the way I usually see it written so I changed it to 2x - 8

Answer 8

I have to find f^-1(y)

Answer 9

Oh the negative so yeah your final answer is f^-1(x) = (8-x)/2 oh this is why we use latex.

Answer 10

No ^_~

It's \(\ \sf \color{blue}{+8} ~ or ~ just~8 \) and \(\ \color{red}{-2x}\) that becomes -2x + 8 or -2x + 8

Answer 11

The problem is Let f(x) = 8 - 2x. Find f^-1(y)

Answer 12

Hmm, never done f(y) before

Answer 13

yeah, I thought it was strange

Answer 14

Simply because f(x) is function of x or y

Answer 15

Do you think that is a typo on the worksheet?

Answer 16

Most likely :3 ask @Luigi0210 <-- My Older Sister knows the way ~

Answer 17

@Luigi0210

Answer 18

Sorry OS just stopped working, but it's the same thing just replace the x and y again.

Answer 19

So instead of x's in your final answers just put y.

Answer 20

I put my final answer as f^-1(x) = (x-8) / 2

Answer 21

No you put f^-1(y) = (y-8)/2

Answer 22

(8-y)/2 not y-8

Answer 23

f^-1(y) = (8-y) / 2

Answer 24

Because he's batman~

Answer 25

so it is the same steps to find the inverse function, you just replace the x's with y's?

Answer 26

Yeah pretty much, just going backwards.

Answer 27

Erm, nope @iambatman , your answer is wrong :3

Answer 28

Elaborate?

Answer 29

@tHe_FiZiCx99

Answer 30

The 2 should be negative.

Answer 31

Do you even algebra? It's the same thing.

Answer 32

Oh look, mr wolfram agrees with me :)

http://www.wolframalpha.com/input/?i=f%28x%29%3D8-2x+inverse