# math

posted by on .

(6) Which equation is equivalent to

4^-x=8?

a. log8 4=x

b. logx = -4

c. log -x 4=8

d. log 4 8= -x

• math - ,

1/4^x = 8
4^x = 1/8
x log4 (4) = log4 (1/8)
but log4 (4) = 1 because b^logb(a) = a
x = log4(1/8) = log4(1) - log4(8)
but log4(1) = 0 for the same reason
so
x = -log4(8) or -x = log4 (8)
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