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:

log_{4} (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

log_{4}(17/4 - 4) = log_{4}(1/4) = -1

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