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If $(7^x − 7^{−x}) / (7^x − 7^{−x}) = y$ then $x =??$.

I do not understand the question. How can we solve and continue with it if it all equals one?

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    You can't. Where is the problem from? You can say $y=1$ unless $x=0$ (in which case the fraction is not defined) – 2017-01-19
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    question number 29 http://www.ucl.ac.uk/clie/placement-tests/UPC/complete.php?exercise=Maths-2 – 2017-01-19
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    You must say : $x\neq.?$ – 2017-01-19

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I suspect they have a typo and the intended question is $$(7^x − 7^{−x}) / (7^x + 7^{−x}) = y$$ Looking at the answers you are supposed to invert the equation by multiplying top and bottom by $7^x,$ solve for $7^x$ and take the base $7$ log to get $x$