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Math Help - Curve Intersections...

  1. #1
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    Curve Intersections...

    A and B are the intersections of the curve y=12/x and the line y+x=7. Find the co-ordinates of A and B. What method do I use for this?
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  2. #2
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    Quote Originally Posted by digideens
    A and B are the intersections of the curve y=12/x and the line y+x=7. Find the co-ordinates of A and B. What method do I use for this?
    You need to solve,
    y=\frac{12}{x}
    x+y=7
    Substitute,
    x+\frac{12}{x}=7
    Mutiply by x to get,
    x^2+12=7x
    Thus,
    x^2-7x+12=0
    Factor,
    (x-3)(x-4)=0
    Set each factor equal to zero and solve,
    x=3,4

    Graphically it is demonstrated below
    Attached Thumbnails Attached Thumbnails Curve Intersections...-untitled.gif  
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  3. #3
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    thanks a lot.
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