Homework Help: precalculus

Posted by Sara on Monday, January 9, 2012 at 6:15pm.

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

precalculus - Reiny, Monday, January 9, 2012 at 6:21pm
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 - Steve, Tuesday, January 10, 2012 at 12:22am
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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