document.write( "Question 909922: If y varies directly as x and inversely as z, what is the effect on y of doubling x and z? \n" ); document.write( "

Algebra.Com's Answer #552153 by Edwin McCravy(20060) $\"\"$ $\"About$

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If y varies directly as x and inversely as z, what is the effect on y of doubling x and z?\r
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document.write( "For all proportion problems, start with this:\r\n" );
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document.write( "Varying           \"directly\" or product of \"jointlys\" or 1 if none \r\n" );
document.write( "quantity  = k · ----------------------------------------------------------\r\n" );
document.write( "                inversely variable or product of \"inverselys\" or 1 if none\r\n" );
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document.write( "In this problem the varying quantity is y.\r\n" );
document.write( "the \"directly\" is x.  We have one inversely, z.  So we have \r\n" );
document.write( "on top and p on the bottom:\r\n" );
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document.write( "        y = k·\r\n" );
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document.write( "Suppose at first substitute x=a and z=b\r\n" );
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document.write( "(1)     y = k·\r\n" );
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document.write( "Now let's double a as 2a and double b as 2b and substitute \r\n" );
document.write( "x = 2a and z=2b\r\n" );
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document.write( "        y = k·\r\n" );
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document.write( "We can cancel the 2's\r\n" );
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document.write( "        y = k·\r\n" );
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document.write( "(2)     y = k·\r\n" );
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document.write( "Now we compare (2) with (1) and we see they are identical.\r\n" );
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document.write( "Answer: There is no effect.\r\n" );
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document.write( "Edwin

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