document.write( "Question 670957: Help with a proof for this: (log base a of x)/(log base a/b of x) = 1+(log base a of 1/b) \n" ); document.write( "
Algebra.Com's Answer #417240 by Theo(13342) You can put this solution on YOUR website! log.a means log to the base of a (my interpretation not generally used). \n" ); document.write( "your equation becomes: \n" ); document.write( "log.a(x) / log.a/b(x) = 1 + log.a(1/b) \n" ); document.write( "you want to prove this identity is true. \n" ); document.write( "you need to use the log base conversion formula of log.d(x) = log.e(x) / log.e(d). \n" ); document.write( "you use this conversion formula on log.a/b(x) to get: \n" ); document.write( "log.a/b(x) = log.a(x) / log.a(a/b) \n" ); document.write( "your equation of: \n" ); document.write( "log.a(x) / log.a/b(x) = 1 + log.a(1/b) becomes: \n" ); document.write( "log.a(x) / (log.a(x) / log.a(a/b)) = 1 + log.a(1/b) \n" ); document.write( "since h/(i/j) is equivalent to h*(j/i), your equation becomes: \n" ); document.write( "log.a(x) * log.a(a/b) / log.a(x) = 1 + log.a(1/b) \n" ); document.write( "since log.a(x) / log.a(x) cancels out, your equation becomes: \n" ); document.write( "log.a(a/b) = 1 + log.a(1/b) \n" ); document.write( "since log(m/n) = log(m) - log(n), your equation becomes: \n" ); document.write( "log.a(a) - log.a(b) = 1 + log.a(1) - log.a(b) \n" ); document.write( "if you add log.a(b) to both sides of the equation, it will cancel out and you'll get: \n" ); document.write( "log.a(a) = 1 + log.a(1) \n" ); document.write( "since log.a(1) = 0, your equation becomes: \n" ); document.write( "log.a(a) = 1 \n" ); document.write( "since log.a(a) = 1, your equation becomes: \n" ); document.write( "1 = 1 which is true confirming the identity as being valid. \n" ); document.write( "log.a(1) is equal to 0 based on the following logic. \n" ); document.write( "log.a(1) = y if and only if a^y = 1 \n" ); document.write( "a^y = 1 if and only if y = 0 \n" ); document.write( "this makes log.a(1) = 0 \n" ); document.write( "log.a(a) is equal to 1 based on the following logic. \n" ); document.write( "log.a(a) = y if and only if a^y = a \n" ); document.write( "a^y = a if and only if y = 1 \n" ); document.write( "this makes log.a(a) = 1 \n" ); document.write( "the key to solving this is the use of the log base conversion formula which is. \n" ); document.write( "log.k(x) = log.p(x) / log.p(k) \n" ); document.write( "as an example, take log.2(8) = 3 \n" ); document.write( "this is true because 2^3 = 8 \n" ); document.write( "convert this to log.10 \n" ); document.write( "log.2(8) = log.10(8) / log.10(2) \n" ); document.write( "use your calculator to see that the answer is going to be 3.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |