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    (a) Solve 2e^x + 2e^-x = 5

    (b) If xy = 64 and logx y (where x is base) + logy x (where y is base) = 5/2 find x and y.

    Also are we allowed the use of a mirror in the P2 exam??

    (Original post by !Laxy!)
    (a) Solve 2e^x + 2e^-x = 5
    Multiplying by e^x gives:
    You have a quadratic in e^x. Solve for e^x and hence find x.

    (b) If xy = 64 and logx y (where x is base) + logy x (where y is base) = 5/2 find x and y.
    If you multiply everything out you'll end up with a quadratic in (lnx) so you can solve to find lnx, x and hence the cooresponding value of y.
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Updated: June 18, 2005
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