document.write( "Question 73404This question is from textbook
\n" ); document.write( ": 1. 3x + y = 6
\n" ); document.write( " x - y = 1\r
\n" ); document.write( "\n" ); document.write( "2. If x Varies directly as y^2, and x= 20 when y= 2, find x when y= 10. \n" ); document.write( "
Algebra.Com's Answer #52526 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "    3x + y = 6\r\n" );
document.write( "     x - y = 1\r\n" );
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\n" ); document.write( "Add the 2 equations. Add 3x to x, y to -y, and 6 to 1
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document.write( "    4x     = 7\r\n" );
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\n" ); document.write( "Now solve for x\r
\n" ); document.write( "\n" ); document.write( "\"4x=7\"
\n" ); document.write( "\"x=7%2F4\"
\n" ); document.write( "Plug this into \"x-y=1\"
\n" ); document.write( "\"%287%2F4%29-y=1\"
\n" ); document.write( "\"-y=1-%287%2F4%29\"
\n" ); document.write( "\"-y=%284-7%29%2F4\"
\n" ); document.write( "\"-y=-3%2F4\"
\n" ); document.write( "\"y=3%2F4\"
\n" ); document.write( "Check:
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document.write( "    3(7/4) + 3/4 = 6\r\n" );
document.write( "      7/4 - 3/4 = 1\r\n" );
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document.write( "    21/4 + 3/4 = 6\r\n" );
document.write( "      4/4 = 1\r\n" );
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document.write( "    24/4 = 6\r\n" );
document.write( "      1=1 Works\r\n" );
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document.write( "      6 = 6 Works\r\n" );
document.write( "      1 = 1 Works\r\n" );
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\n" ); document.write( "\n" ); document.write( "Since x varies directly as y^2, the equation looks like
\n" ); document.write( "\"y%5E2=kx\"
\n" ); document.write( "So just plug in x=20 and y=2 to find k
\n" ); document.write( "\"2%5E2=k%2A20\"
\n" ); document.write( "\"4%2F20=k\"
\n" ); document.write( "\"k=1%2F5\"
\n" ); document.write( "Now plug k into the equation to find x when y=10
\n" ); document.write( "\"y%5E2=%281%2F5%29x\"
\n" ); document.write( "\"10%5E2=%281%2F5%29x\"Plug in y=10
\n" ); document.write( "\"5%2A10%5E2=x\"
\n" ); document.write( "\"x=500\" \n" ); document.write( "

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