document.write( "Question 1140061: If 2^x = 4^y = 8^z and 1/(2x) + 1/(4y) + 1/(8z) = 22/7. Show that x = 7/16, y = 7/32 and z = 7/48. \n" ); document.write( "
Algebra.Com's Answer #760520 by KMST(5328)\"\" \"About 
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ONE WAY:
\n" ); document.write( "We know \"x%3C%3E0\" , \"y%3C%3E0\" and \"z%3C%3E0\" because otherwise they would make the denominators zero, and the expression \"1%2F%282x%29+%2B+1%2F%284y%29+%2B+1%2F%288z%29\" would not exist as a real number.
\n" ); document.write( "As \"4=2%5E2\" and \"8=2%5E3\" ,
\n" ); document.write( "if \"2%5Ex+=+4%5Ey+=+8%5Ez\" ,
\n" ); document.write( "\"2%5Ex+=+4%5Ey+=+%282%5E2%29%5Ey+=+2%5E%282y%29\" ,
\n" ); document.write( "and \"2%5E%282y%29%2F2%5Ex=2%5E%282y-x%29=1+meaning+that+%7B%7B%7B2y-x=0\" , \"x=2y\" , and \"y=%281%2F2%29x\".
\n" ); document.write( "Also \"2%5Ex+=+8%5Ez+=+%282%5E3%29%5Ez+=+2%5E%283z%29\" , which means \"x=3z\" , and \"z=%281%2F3%29x\" .
\n" ); document.write( "You could also talk about taking logarithms base 2.\ to get to the same conclusions.
\n" ); document.write( "Then, substituting into \"1%2F%282x%29+%2B+1%2F%284y%29+%2B+1%2F%288z%29+=+22%2F7\" , we get
\n" ); document.write( "\"1%2F%282x%29+%2B+1%2F%284%281%2F2%29x%29+%2B+1%2F%288z%29+=+22%2F7\"
\n" ); document.write( "\"1%2F%282x%29+%2B+1%2F%282x%29+%2B+1%2F%288z%29+=+22%2F7\"
\n" ); document.write( "\"1%2Fx+%2B+1%2F%288z%29+=+22%2F7\"
\n" ); document.write( "\"1%2F%283z%29+%2B+1%2F%288z%29+=+22%2F7\"
\n" ); document.write( "Multiplying both sides of the equation times the non-zero number \"3%2A8%2A7%2Az\" ,
\n" ); document.write( "we get the equivalent equation
\n" ); document.write( "\"8%2A7%2B3%2A7=22%2A3%2A8%2Az\"
\n" ); document.write( "\"%288%2B3%29%2A7=22%2A3%2A8%2Az\"
\n" ); document.write( "\"11%2A7=2%2A11%2A3%2A8%2Az\"
\n" ); document.write( "\"7%2F%282%2A3%2A8%29=z\"
\n" ); document.write( "\"highlight%28z=7%2F48%29\"
\n" ); document.write( "Then, as \"x=3z\" , \"x=3%2A7%2F%282%2A3%2A8%29=7%2F%282%2A8%29=highlight%287%2F16%29\" ,
\n" ); document.write( "and as \"y=%281%2F2%29x\" , \"y=%281%2F2%29%2A%287%2F16%29=highlight%287%2F32%29\"
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