Precalculus

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Suppose f(x) = 3^x
a) Find x where f(x) = 1/27.
b) Estimate the value of x where
f(x) = 24.

So,
a) f(x) = 3^x
f(1/27) = 3^1/27
b) f(x) = 3^x
f(24) = 3^24

Don't know how to solve them :( Please Help!!

  • Precalculus -

    a) If 3^x = 1/27, then x = 1/3
    Check it out: does (1/3)^3 = 27?

    b) They are NOT asking for f(24) They are asking for the value of x for which f(4) = 3^x = 24. You seem to be confused by the function notation.

    If f(x) = 3^x = 24, then
    x log 3 = log 24
    x = log 24/log 3 = 1.38021/0.47712
    = 2.8928

    Check: 3^2.8928 = 24.000

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