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Graph Qs

  • 10-11-2012 4:26pm
    #1
    II 2FAST2C II
    Site Banned Posts: 104 ✭✭


    Hi
    I am stuck in a 2001 Exam paper i was just revising and i cam across some problems in sum which i could not figure out i even checked the markin schemes but did not get it how it was done
    Some of the qs i am stuck in is
    Q.3(a)(iii)
    Q.5(a)(i) and (ii) (I have drawn the graphs all right and everything i just do not know how to solve them)
    Q.5(b)(ii) and (iii)

    If anyone can help it would be greatly appreciated


Comments

  • #2
    TheBody
    Registered Users, Registered Users 2 Posts: 5,633 ✭✭✭TheBody


    II 2FAST2C II wrote: »
    Hi
    I am stuck in a 2001 Exam paper i was just revising and i cam across some problems in sum which i could not figure out i even checked the markin schemes but did not get it how it was done
    Some of the qs i am stuck in is
    Q.3(a)(iii)
    Q.5(a)(i) and (ii) (I have drawn the graphs all right and everything i just do not know how to solve them)
    Q.5(b)(ii) and (iii)

    If anyone can help it would be greatly appreciated

    For Q.3(a)(iii) just use the formula for factorising the difference of two squares.

    For Q.5(a)(i) this is saying to you, if you have an x value of 2.5, what is the corresponding y value. Just use the graph to do this.

    For Q.5(a)(ii) The roots of a function are visually located where the graph cuts the x-axis. Just read the values off the graph.

    Q.5(b)(ii) This is much the same as above. g(x)=0 is the same thing as asking to find the roots of g(x). So let [latex]9-x^2=0 [/latex] and solve for x.

    Q.5(b)(iii)For the left hand side, find g(x). For the right hand side, first find g(2) and then run that value through g again. Hopefully the left will be greater than the right!


  • #3
    II 2FAST2C II
    Site Banned Posts: 104 ✭✭II 2FAST2C II


    Thank you,
    You do not mind helping me in one more small Qs.http://www.examinations.ie/archive/markingschemes/2007/JC003ALP100EV.pdf
    If you could go on Qs 2. Part C
    I got all the number in the diagram but i do not get how they got 3+x
    This is how i got all the others
    22-10=12-2x for MP3
    22-11=11-2x for dig cam
    24-10-11= to get 3 but do not know how they got +x
    Please help and thank you for previous help


  • #4
    MathsManiac
    Registered Users, Registered Users 2 Posts: 1,595 ✭✭✭MathsManiac


    the 10 and the 11 overlap in the middle. So if you take both the 10 and the 11 from the 24, you've subtracted these people twice, so you have to put them back in again once.

    Another way of looking at it is that the regions you already know in the CD bubble are (10-x), (11-x), and x. So the remaining bit is 24 - (10-x) - (11-x) - x, which gives 3+x.


  • #5
    TheBody
    Registered Users, Registered Users 2 Posts: 5,633 ✭✭✭TheBody


    Sorry II 2FAST2C II, I just realised I forgot to get back to you on the second problem. Thanks to MathsManiac for jumping in there.


  • #6
    II 2FAST2C II
    Site Banned Posts: 104 ✭✭II 2FAST2C II


    TheBody wrote: »
    Sorry II 2FAST2C II, I just realised I forgot to get back to you on the second problem. Thanks to MathsManiac for jumping in there.

    Its ok you already done me a huge favour same as mathsmaniac


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  • #7
    ConorCBS
    Registered Users, Registered Users 2 Posts: 1,410 ✭✭✭ConorCBS


    TheBody wrote: »
    Sorry II 2FAST2C II, I just realised I forgot to get back to you on the second problem. Thanks to MathsManiac for jumping in there.

    Are you a maths teacher?


  • #8
    TheBody
    Registered Users, Registered Users 2 Posts: 5,633 ✭✭✭TheBody


    ConorCBS wrote: »
    Are you a maths teacher?

    Sort of. I work in a university maths dept.


  • #9
    ConorCBS
    Registered Users, Registered Users 2 Posts: 1,410 ✭✭✭ConorCBS


    TheBody wrote: »

    Sort of. I work in a university maths dept.

    Can you do Leaving Cert maths? :P


  • #10
    TheBody
    Registered Users, Registered Users 2 Posts: 5,633 ✭✭✭TheBody


    ConorCBS wrote: »
    Can you do Leaving Cert maths? :P

    Sure I'd give it a go!! I can be mad busy at times, so it can be hit or miss when I'm free to post. You might get a faster reply in the maths forum:

    http://www.boards.ie/vbulletin/forumdisplay.php?f=380

    Lots of great posters over there.


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