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Maths Ex Help

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  • 18-04-2015 12:15am
    #1
    2Fast2C
    Registered Users Posts: 15 ✭


    Could someone please tell me how to work out this qs.

    I cannot post attatchments but its on pg 50 qs7 all and 9 part 3 text and tests 7


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    #2
    is mise spartacus
    Registered Users Posts: 1,027 ✭✭✭is mise spartacus


    7
    i) x=-2,1,3
    ii) x=1.4 or x=2.8
    iii) x³-2x²-5x=0 -> x²-2x-5x+6=0+6=6
    Y=6 x=-1.5 or x=0
    No: because a horizontal line will cut the graph at more than one point
    Surjective: any horizontal line will cut the graph at least once


    9 iii) limx³-64 ÷x²-16 = x²+4x+16÷x+4
    = (4)²+4(4)+16÷4+4 = 48÷8= 6


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    #3
    2Fast2C
    Registered Users Posts: 15 ✭2Fast2C


    is mise spartacus wrote: »
    7
    i) x=-2,1,3
    ii) x=1.4 or x=2.8
    iii) x³-2x²-5x=0 -> x²-2x-5x+6=0+6=6
    Y=6 x=-1.5 or x=0
    No: because a horizontal line will cut the graph at more than one point
    Surjective: any horizontal line will cut the graph at least once


    9 iii) limx³-64 ÷x²-16 = x²+4x+16÷x+4
    = (4)²+4(4)+16÷4+4 = 48÷8= 6

    Hi, thank you so much for the help, but can you tell me how you got the answers for part (i) and (ii) in Q7


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    #4
    2Fast2C
    Registered Users Posts: 15 ✭2Fast2C


    BUMP


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    #5
    is mise spartacus
    Registered Users Posts: 1,027 ✭✭✭is mise spartacus


    For i) If you look at the graph and you will see 6 black dots. The black dots at 0 on the x axis are -2, 1 and 3. This is the answer because f(x)=0

    For ii) Again look at the graph, this time on the Y axis. The second line from o says -4, above this at the next line, draw a horizontal line. This will be your -2. Where that line touches off the red line place line up touching the x axis. This will roughly show the answer as 1.4 and 2.8

    I hope my explanation isn't too complicated :o


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    #6
    2Fast2C
    Registered Users Posts: 15 ✭2Fast2C


    is mise spartacus wrote: »
    For i) If you look at the graph and you will see 6 black dots. The black dots at 0 on the x axis are -2, 1 and 3. This is the answer because f(x)=0

    For ii) Again look at the graph, this time on the Y axis. The second line from o says -4, above this at the next line, draw a horizontal line. This will be your -2. Where that line touches off the red line place line up touching the x axis. This will roughly show the answer as 1.4 and 2.8

    I hope my explanation isn't too complicated :o[/QUOTE
    GOT IT THANKS A MILL !!


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