document.write( "Question 828151: Suppose that x varies directly as z and that y also varies directly as z.\r
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document.write( "(A) does x + y vary directly as as z?
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document.write( "(B) does xy vary directly as z?
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document.write( "(C) does sqrt(xy) vary directly as z? Assume x, y and z are positive.\r
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document.write( "The answers are yes, no, yes respectively.\r
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document.write( "I don't really understand why the answer isn't 'yes' for all the questions. I'm thinking that the formula I should work with is z = kxy. Could you please explain to me these answers? Thank you in advance. \n" );
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Algebra.Com's Answer #499070 by Alan3354(69443)![]() ![]() You can put this solution on YOUR website! Suppose that x varies directly as z and that y also varies directly as z.\r \n" ); document.write( "\n" ); document.write( "(A) does x + y vary directly as as z? \n" ); document.write( "(B) does xy vary directly as z? \n" ); document.write( "(C) does sqrt(xy) vary directly as z? Assume x, y and z are positive.\r \n" ); document.write( "\n" ); document.write( "The answers are yes, no, yes respectively.\r \n" ); document.write( "\n" ); document.write( "I don't really understand why the answer isn't 'yes' for all the questions. I'm thinking that the formula I should work with is z = kxy. \n" ); document.write( "----------------- \n" ); document.write( "For B, xy varies \"directly\" as z in the sense that when z increases xy increases. \n" ); document.write( "But, since xy is a product it varies as the square of z. \n" ); document.write( "If z is doubled, both x and y are doubled --> xy is 4 times. \n" ); document.write( " |