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# CORE 3 Composite functions Watch

1. Hey...
I have this question:
The function f is defined by f(x) = | x – 2 | – 3

g(x) = x^2 – 4x + 11

Question - Find gf(–1).

I was wondering, for this question i got:

| x^2 - 4x + 11 - 2| - 3

When substituting in the value of x as -1, why do you not need to consider the positive and negative values i.e. + (x^2 - 4x + 11 - 2) - 3
and -(x^2 -4x + 11 - 2) - 3 ??
2. Forgive me if I'm wrong, but isn't that f o g?
3. (Original post by stanmoor)
Hey...
I have this question:
The function f is defined by f(x) = | x – 2 | – 3

g(x) = x^2 – 4x + 11

Question - Find gf(–1).

I was wondering, for this question i got:

| x^2 - 4x + 11 - 2| - 3

When substituting in the value of x as -1, why do you not need to consider the positive and negative values i.e. + (x^2 - 4x + 11 - 2) - 3
and -(x^2 -4x + 11 - 2) - 3 ??

You have to put f into g :
Actually you could even do

F(-1) first and whet ever that equals put that in for x in g(x)
4. hmmm i got (|x-2|-3)^2 - 4(|x-2|-3) +11

so when x= -1

0 - 0 + 11

answer is 11? i dunno tbh, gd luck
5. (Original post by stanmoor)
Hey...
I have this question:
The function f is defined by f(x) = | x – 2 | – 3

g(x) = x^2 – 4x + 11

Question - Find gf(–1).

I was wondering, for this question i got:

| x^2 - 4x + 11 - 2| - 3

When substituting in the value of x as -1, why do you not need to consider the positive and negative values i.e. + (x^2 - 4x + 11 - 2) - 3
and -(x^2 -4x + 11 - 2) - 3 ??
Just go the ****ing easy way

6. (Original post by stanmoor)
Hey...
I have this question:
The function f is defined by f(x) = | x – 2 | – 3

g(x) = x^2 – 4x + 11

Question - Find gf(–1).

I was wondering, for this question i got:

| x^2 - 4x + 11 - 2| - 3

When substituting in the value of x as -1, why do you not need to consider the positive and negative values i.e. + (x^2 - 4x + 11 - 2) - 3
and -(x^2 -4x + 11 - 2) - 3 ??
The answer is 11. You do f(-1) which is | -3 | - 3 (Modulus of -3 is 3, so 3 - 3)
then you do g(0) = = 11.
7. (Original post by stanmoor)
Hey...
I have this question:
The function f is defined by f(x) = | x – 2 | – 3

g(x) = x^2 – 4x + 11

Question - Find gf(–1).

I was wondering, for this question i got:

| x^2 - 4x + 11 - 2| - 3

When substituting in the value of x as -1, why do you not need to consider the positive and negative values i.e. + (x^2 - 4x + 11 - 2) - 3
and -(x^2 -4x + 11 - 2) - 3 ??
the people who are giving 11 as the final answer are right i believe

the reason you dont consider the positive AND negative values is because you square the modulus which will always give a positive answer (negative squared = positive)
8. Sorry, are people unable to read here? I gave the answer in a clear form and jimimick got it before me but did it in a frankly awkward way.
9. (Original post by alexs2602)
Sorry, are people unable to read here? I gave the answer in a clear form and jimimick got it before me but did it in a frankly awkward way.
I don't really understand what you are trying to say. Do you really mean no one can post after you even if they think they might contribute a bit to OP's understanding of the topic? No one gave you negative rep nor said anything negative about you.
10. (Original post by Chelle-belle)
I don't really understand what you are trying to say. Do you really mean no one can post after you even if they think they might contribute a bit to OP's understanding of the topic? No one gave you negative rep nor said anything negative about you.
I'm saying; "why answer a question twice?"

Plus it feels like I'm being ignored as you've answered the same as what I've said twice in the last hour; on this thread and stanmoor's log thread.
11. (Original post by alexs2602)
I'm saying; "why answer a question twice?"

Plus it feels like I'm being ignored as you've answered the same as what I've said twice in the last hour; on this thread and stanmoor's log thread.
Maybe your posts were inadequate or people still felt they could contribute. Furthermore, why not answer a question twice (if it is the first time for the one answering it) if you have nothing else to do, and come to this forum specifically to answer questions, anyway? I could just as easily ask you why you bothered to come back to this thread, and the other thread, and probably a few other threads, for no apparent reason, and why you bothered to post something like this.

And I probably did ignore you on the other thread, not that you should take offense to that, since a) I ignore most posts without some sort of actual explanation (which is why I later deleted my post); b) it shouldn't really affect you directly.
12. (Original post by Chelle-belle)
Maybe your posts were inadequate or people still felt they could contribute. Furthermore, why not answer a question twice (if it is the first time for the one answering it) if you have nothing else to do, and come to this forum specifically to answer questions, anyway?
Impossible, my answers are pretty clear. And fine if you want to elaborate but reiterating is pointless.
13. Thanks alot viksta1000 you answered my question!
14. (Original post by stanmoor)
Thanks alot viksta1000 you answered my question!
whoever neg'd your post is a jealous mo'fo

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