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Core 3

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Reply 20
Original post by Ayaz789
Complete the square on what? On f(x)?


Sketch the graph of fg(x). What is the domain of this function? Hence, what is it's corresponding range?
Reply 21
Original post by Zacken
Sketch the graph of fg(x). What is the domain of this function? Hence, what is it's corresponding range?


Im going to have to do all that for 1 mark? Well not even 1 mark , idek if we lose a mark :frown:
Reply 22
Original post by Ayaz789
Im going to have to do all that for 1 mark? Well not even 1 mark , idek if we lose a mark :frown:


Having properly read the question, where do you get -16 from? The range is [-25, ifinity).
Reply 23
Original post by Zacken
Having properly read the question, where do you get -16 from? The range is [-25, ifinity).


(-16, infinity) the range of fg?
Reply 24
Original post by Ayaz789
(-16, infinity) the range of fg?


Yeah, how do you get that?
Reply 25
Original post by Zacken
Yeah, how do you get that?


Because i got the domain of g and put into the function of G then put the range of g into the function of f(X)
Reply 26
Original post by Ayaz789
Because i got the domain of g and put into the function of G then put the range of g into the function of f(X)


Yeah, and you get that the minimum value of f(x) is clearly -25 which occurs when g(x) = 0 which occurs within the domain of g(x).
Reply 27
Original post by Zacken
Yeah, and you get that the minimum value of f(x) is clearly -25 which occurs when g(x) = 0 which occurs within the domain of g(x).


Okay nw , ill just do what i can in the exam!
Reply 28
Original post by IrrationalRoot
[a,b] means all the real numbers between a and b including a and b.
(a,b) means all the real numbers between a and b excluding a and b.
[a,b) means all the real numbers between a and b including a and excluding b.
(a,b] means all the real numbers between a and b excluding a and including b.
Of course, if a or b are ±infinity, then there will be a round bracket because obviously infinity is not included.

That's about as comprehensive of an explanation you can get.


Thanks for trying to help me , somethings just don't go into me , this is 1 of them , sorry!
Original post by Ayaz789
Thanks for trying to help me , somethings just don't go into me , this is 1 of them , sorry!


But it's so simple...
Reply 30
Original post by IrrationalRoot
But it's so simple...


I do further maths too which makes it worse :O and im going to study maths at Uni which makes me sounds awful at maths!:/
Original post by Ayaz789
I do further maths too which makes it worse :O and im going to study maths at Uni which makes me sounds awful at maths!:/


Tbf this is nothing about maths ability, so dw in that respect.
But it is common sense lol.
Reply 32
Original post by IrrationalRoot
Tbf this is nothing about maths ability, so dw in that respect.
But it is common sense lol.


Yeahh,i understand it a bit now, that if its square its including the number , if its a curved then its between that number and the the other bracket , well you tried to help!:smile:
Original post by Ayaz789
Yeahh,i understand it a bit now, that if its square its including the number , if its a curved then its between that number and the the other bracket , well you tried to help!:smile:


There we go! :smile:
Reply 34
Original post by IrrationalRoot
There we go! :smile:

Is that right?:biggrin:
Original post by Ayaz789
Is that right?:biggrin:


You are asking 'how do I know what the 'range of values is going to be', as opposed to the issue of notation - i.e what [ ] and ( ) etc mean.

You just work it out from the question or whatever's being asked. Eg if I asked you what the domain of lnx is, then you know that since lnx is undefined for x less than or equal to 0, you get that x>0 so the domain is (0,infinity]
Reply 36
Original post by SeanFM
You are asking 'how do I know what the 'range of values is going to be', as opposed to the issue of notation - i.e what [ ] and ( ) etc mean.

You just work it out from the question or whatever's being asked. Eg if I asked you what the domain of lnx is, then you know that since lnx is undefined for x less than or equal to 0, you get that x>0 so the domain is (0,infinity]


Wont it be (0, infinity)
Original post by Ayaz789
Wont it be (0, infinity)


:s-smilie: that is a can of worms for me, I'm afraid :tongue:
Reply 38
Original post by SeanFM
:s-smilie: that is a can of worms for me, I'm afraid :tongue:


Haha am i right?
Original post by Ayaz789
Haha am i right?


As long as you see the point I am trying to illustrate. Eg domain (for real values of x) of x \sqrt x = ..
(edited 7 years ago)

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