# precalculus

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solve the following equation show all work log4(x-4)= -1.

• precalculus -

by definition:

log4 (x-4) = -1
is equivalent to
x-4 = 4^-1
x-4 = 1/4
x = 1/4 - 4
= -15/4

so we would have log (-3/4-4)
but we cannot take the log of a negative, so ....
no solution.

• precalculus -

log takes on all real values for its range. So, something's wrong here.

x - 4 = 1/4
x = 1/4 + 4
x = 17/4

log4(17/4 - 4) = log4(1/4) = -1

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