document.write( "Question 617078: Please help me \r
\n" ); document.write( "\n" ); document.write( "Solve for all values of x, to the nearest 10th.
\n" ); document.write( "log4(2x−7)+log4(3x−3)=4
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Algebra.Com's Answer #388107 by jsmallt9(3758)\"\" \"About 
You can put this solution on YOUR website!
Assuming these are base 4 logarithms...
\n" ); document.write( "\"log%284%2C+%282x-7%29%29%2Blog%284%2C+%283x-3%29%29=4\"
\n" ); document.write( "We want the equation in the form
\n" ); document.write( "log(expression) = other-expression
\n" ); document.write( "So we will use a property of logarithms, \"log%28a%2C+%28p%29%29%2Blog%28a%2C+%28q%29%29+=+log%284%2C+%28p%2Aq%29%29\", to combine the logarithms:
\n" ); document.write( "\"log%284%2C+%28%282x-7%29%283x-3%29%29%29=4\"

\n" ); document.write( "Now that the equation is in the desired form, the next step is to rewrite the equation in exponential form. In general \"log%28a%2C+%28p%29%29+=+q\" is equivalent to \"a%5Eq+=+p\". Using this pattern on our equation we get:
\n" ); document.write( "\"4%5E4+=+%282x-7%29%283x-3%29\"
\n" ); document.write( "which simplifies to:
\n" ); document.write( "\"256+=+6x%5E2-27x%2B21\"

\n" ); document.write( "Now that the variable is out of the logarithm, we can solve for it. This is a quadratic equation so we want one side to be zero. Subtracting 256 from each side:
\n" ); document.write( "\"0+=+6x%5E2-27x-235\"
\n" ); document.write( "Next we factor or use the Quadratic Formula. This will not factor so we must use the formula:
\n" ); document.write( "\"x+=+%28-%28-27%29+%2B-+sqrt%28%28-27%29%5E2+-+4%286%29%28-235%29%29%29%2F2%286%29\"
\n" ); document.write( "Simplifying...
\n" ); document.write( "\"x+=+%28-%28-27%29+%2B-+sqrt%28729+-+4%286%29%28-235%29%29%29%2F2%286%29\"
\n" ); document.write( "\"x+=+%28-%28-27%29+%2B-+sqrt%28729+-+%28-5640%29%29%29%2F2%286%29\"
\n" ); document.write( "\"x+=+%28-%28-27%29+%2B-+sqrt%28729+-+%28-5640%29%29%29%2F2%286%29\"
\n" ); document.write( "\"x+=+%28-%28-27%29+%2B-+sqrt%286369%29%29%2F2%286%29\"
\n" ); document.write( "\"x+=+%2827+%2B-+sqrt%286369%29%29%2F12\"
\n" ); document.write( "So \"x+=+%2827+%2B+sqrt%286369%29%29%2F12\" or \"x+=+%2827+-+sqrt%286369%29%29%2F12\"

\n" ); document.write( "Since you were asked for decimal answers, get out your calculator and round off your answer to the nearest tenth.\r
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