document.write( "Question 309381: I do not have a very large understanding of logarithms, and i can't solve the question:\r
\n" ); document.write( "\n" ); document.write( "log 7 + log x = 2\r
\n" ); document.write( "\n" ); document.write( "(The answer is 100/7)\r
\n" ); document.write( "\n" ); document.write( "I can solve things such as log x - log 6 = log 15 without having to worry about the base 10, but i do not understand when i need to use it to get the right answer. \n" ); document.write( "
Algebra.Com's Answer #221275 by CharlesG2(834)\"\" \"About 
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\"I do not have a very large understanding of logarithms, and i can't solve the question:
\n" ); document.write( "log 7 + log x = 2
\n" ); document.write( "(The answer is 100/7)
\n" ); document.write( "I can solve things such as log x - log 6 = log 15 without having to worry about the base 10, but i do not understand when i need to use it to get the right answer.\"\r
\n" ); document.write( "\n" ); document.write( "log 7 + log x = 2
\n" ); document.write( "means
\n" ); document.write( "log10 7 + log10 x = 2
\n" ); document.write( "the 10 is your base (b)
\n" ); document.write( "logarithmic rule: logb (mn) = logb (m) + logb (n)
\n" ); document.write( "so we have
\n" ); document.write( "log10 (7x) = 2
\n" ); document.write( "logarithmic rule: logb (y) = x is equivalent to b^x = y
\n" ); document.write( "so we have
\n" ); document.write( "10^2 = 7x
\n" ); document.write( "100 = 7x
\n" ); document.write( "100/7 = x
\n" ); document.write( "hope this helps
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