Question

f(x)=X-4/x, and f(2b)=2f(b), then b is? solutions..?

Answer 1

manoranjan! help

Answer 2

see solve the equation 2x-4/2x=2[x-4/x]

Answer 3

inconsistent, no?

Answer 4

the answer in d reviewer is 6,.. but what is the solution to get 6?

Answer 5

If b is 6 then f(6) = 5 1/3

*2 = 10 2/3

but f(12) is 11 2/3

so b is not 6.

Answer 6

Zion, is this the right equation??
\[f(x)=X-\frac{4}{x}\]
does capital X have a known value?? As written, there is no solution, so maybe there's a typo ?

Answer 7

if on the other hand, the equation is
\[f(x)= \frac{x-4}{x}\]
we can solve it.

Answer 8

thats the equation!

Answer 9

how did u do that,.. coz i dont know how to type that equation here

Answer 10

In the equation editor, you can type "\"frac (without the quotes!){top}{bottom}

Answer 11

so whats the solution to my question?

Answer 12

But back to the problem. If we use
\[f(x)=\frac{x-4}{x}\]
substitute 2b for x. Try it!

Answer 13

i still dont know how

Answer 14

to do what?

Answer 15

what im going to do.

Answer 16

OK, here's the big picture...

Answer 17

Still not going to work for 6, is it?

Answer 18

you have a function f(x) = (x-4)/x

Answer 19

then...?

Answer 20

This means wherever you see an x, you can replace it.. I mean if you have f(b), you replace the x with a b...
or if you have f(2b), replace the x with 2b.

Answer 21

So the very first thing to do is f(b) and then f(2b). Give it a shot.

Answer 22

Here's f(b)
f(b)= (b-4)/b
do the same for f(2b). Then on to the next step

Answer 23

Did I lose you?

Answer 24

f(x)=(x-4)/x
f(2b)=(2b-4)/2b

f(2b)= 2 f(b)

f(2b)=f(2b]
(2b-4)/2b = 2(b-4)/b
cross multiply
b(2b-4) = 2b(2b-8)
cancel b on both sides
2b-4 = 2(2b-8)
2b-4 = 4b-16
group similar terms
4b-2b = 16-4
2b = 12
b = 6

Answer 25

Yes It looks good. No, it looks very good!
But you aren't zion.