Question

14. Solve without the calculator: log

8
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(x+1)+log
8
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(x−1)=1 15. Solving the following system of equations using any method. Show each step clearly.
X+2Y+4Z=1
2X+Y+2Z=5
3X−3Y−2Z=8
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Answer 1

Explanation:

log8 (x+1) + log8 (x-1) = 1

Using rules of logs, this is the same as

log8 ( (x+1)(x-1) ) = 1

log8 ( x^2 -1) = 1 Use rules of logs again to reduce to:

x^2- 1 = 8^1

x^2 = 9

x = ± 3

x = +3 ( -3 would make a negative log...not allowed)