C3 functions

Original post by bigdonger

\dfrac{any\ number}{0}

so how can i do this one?

What's the range of f(x)?

Reply 2

math42

Original post by bigdonger

\dfrac{any\ number}{0}

so how can i do this one?

look at behaviour of f as x gets closer and closer to 1/2

Reply 3

B_9710

The domain of the inverse function is the same as the range of the original function.

Reply 4

Original post by RDKGames

What's the range of f(x)?

that's my point how can i do that? usually i would put 0.5 into f(x) but that doesn't work because you can't have 1/0 it doesn't work so how can i have a range for this?

Original post by 1 8 13 20 42

look at behaviour of f as x gets closer and closer to 1/2

if i put 1 in i get 1 out
if i put -1 in i get -1 out
if i put 1/4 in i get -2 out
if i put 1/3 in i get -3 out
if i put in 0.4 i get -5 out
if i put 0.45 in i get -10 out
if i put in 3/4 in i get 2 out
if i put 0.55 in i get 10 out

i can't see anything besides the fact tat when i get closer to 0.5 the range seems to be infinitely huge

Reply 5

[QUOTE=bigdonger;66453208]that's my point how can i do that? usually i would put 0.5 into f(x) but that doesn't work because you can't have 1/0 it doesn't work so how can i have a range for this?

if i put 1 in i get 1 out
if i put -1 in i get -1 out
if i put 1/4 in i get -2 out
if i put 1/3 in i get -3 out
if i put in 0.4 i get -5 out
if i put 0.45 in i get -10 out
if i put in 3/4 in i get 2 out
if i put 0.55 in i get 10 out

i can't see anything besides the fact tat when i get closer to 0.5 the range seems to be infinitely huge

But that's exactly it. Range is everything real except 0.5.

Reply 6

Original post by B_9710

The domain of the inverse function is the same as the range of the original function.

I did just say this in my original post >.>

Original post by RDKGames

But that's exactly it. Range is everything real except 0.5.

No that's the domain which is stated in the question....

Reply 7

B_9710

Original post by bigdonger

I did just say this in my original post >.>

No that's the domain which is stated in the question....

Sketch the graph then if you can't immediately find the range of f.

Reply 8

math42

Original post by bigdonger

that's my point how can i do that? usually i would put 0.5 into f(x) but that doesn't work because you can't have 1/0 it doesn't work so how can i have a range for this?

if i put 1 in i get 1 out
if i put -1 in i get -1 out
if i put 1/4 in i get -2 out
if i put 1/3 in i get -3 out
if i put in 0.4 i get -5 out
if i put 0.45 in i get -10 out
if i put in 3/4 in i get 2 out
if i put 0.55 in i get 10 out

i can't see anything besides the fact tat when i get closer to 0.5 the range seems to be infinitely huge

Exactly, the range has no upper bound, only a lower bound, can you see what it is?

Reply 9

Original post by B_9710

Sketch the graph then if you can't immediately find the range of f.

ewww i hate sketching graphs especially stuff like this

Original post by 1 8 13 20 42

Exactly, the range has no upper bound, only a lower bound, can you see what it is?

i'm sure it doesnt have an upper or lower bound... if i put in numbers close but smaller than 0.5 i get big negative values if i put in numbers closer but bigger than 0.5 i get bit positive numbers so i'm not seeing anything here apart from the range could be something stupidly high

Reply 10

math42

Original post by bigdonger

ewww i hate sketching graphs especially stuff like this

i'm sure it doesnt have an upper or lower bound... if i put in numbers close but smaller than 0.5 i get big negative values if i put in numbers closer but bigger than 0.5 i get bit positive numbers so i'm not seeing anything here apart from the range could be something stupidly high

But x > 1/2, read part a) again
edit: well not part a, start of the question

Reply 11

Original post by 1 8 13 20 42

But x > 1/2, read part a) again
edit: well not part a, start of the question

ah so what comes out the otherside are just ridiculously huge numbers

Reply 12

[QUOTE=bigdonger;66453380]ewww i hate sketching graphs especially stuff like this

i'm sure it doesnt have an upper or lower bound... if i put in numbers close but smaller than 0.5 i get big negative values if i put in numbers closer but bigger than 0.5 i get bit positive numbers so i'm not seeing anything here apart from the range could be something stupidly high

Okay you are confusing me. Here's what's what. For original; domain x>0.5, range y>0. So for inverse the domain will be X>0

Reply 13

Original post by RDKGames

Okay you are confusing me. Here's what's what. For original; domain x>0.5, range y>0. So for inverse the domain will be X>0

wat where does y.0 come from... ?????????????

Reply 14

Original post by bigdonger

wat where does y.0 come from... ?????????????

That's the range...

Reply 15

hellomynameisr

Perhaps watch the exam solutions vid on the questions...

He explains it pretty well

Reply 16

Original post by RDKGames

That's the range...

and where does it come from?

Reply 17

[QUOTE=bigdonger;66453592]and where does it come from?

Look at the equation. Nothing will make it equal 0 because numerator is 1 hence it cannot be equal 0. From the domain you can work out whether it is more or less than 0

Reply 18