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OCR Maths Core 3 question!

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    http://pdf.ocr.org.uk/download/pp_08..._gce_4723.pdf?


    The very very last question please 9iii) where it says show that the gradient is -1

    i'm up to the point where i've got x^4-5x^2+100=0

    but what do I do from there?
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    Try substituting x^2 for u, the rest ought to become clear.
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    Set dy/dx as -1 and then move that over to the other side to make dy/dx=0. Then work out the discriminant and it should be negative - meaning no real roots.

    And btw - its asking you to show the gradient is NEVER -1

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Updated: June 9, 2012
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