document.write( "Question 67784This question is from textbook An incremental Development
\n" ); document.write( ": please help to solve\r
\n" ); document.write( "\n" ); document.write( "x + 3y = 7
\n" ); document.write( "xy = 2 \n" ); document.write( "
Algebra.Com's Answer #48298 by ankor@dixie-net.com(22740)\"\" \"About 
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please help to solve
\n" ); document.write( "x + 3y = 7
\n" ); document.write( "Solve for x:
\n" ); document.write( "x = (7 - 3y)
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\n" ); document.write( "Substitute (7-3y) for x in:
\n" ); document.write( "xy = 2
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\n" ); document.write( "(7-3y) * y = 2
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\n" ); document.write( "7y - 3y^2 = 2
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\n" ); document.write( "Arrange as a quadratic equation:
\n" ); document.write( "-3y^2 + 7y - 2 = 0
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\n" ); document.write( "Easier to factor if the 3y^2 is positive, multiply equation by -1
\n" ); document.write( "3y^2 - 7y + 2 = 0
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\n" ); document.write( "Factors to:
\n" ); document.write( "(3y-1)(y-2) = 0
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\n" ); document.write( "Two solutions for y
\n" ); document.write( "3y = +1
\n" ); document.write( "y = (1/3)
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\n" ); document.write( "y = +2
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\n" ); document.write( "Find the value of x using y = (1/3):
\n" ); document.write( "x + 3y = 7
\n" ); document.write( "x + 3(1/3) = 7
\n" ); document.write( "x + 1 = 7 - 1
\n" ); document.write( "x = +6
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\n" ); document.write( "Find the value of x using y = 2
\n" ); document.write( "x + 3y = 7
\n" ); document.write( "x + 3(2) = 7
\n" ); document.write( "x + 6 = 7
\n" ); document.write( "x = 7 - 6
\n" ); document.write( "x = +1
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\n" ); document.write( "We have two solution coordinates. x = 6: y =(1/3) and x = 1, y = 2
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\n" ); document.write( "Note that both will satisfy the xy = 2 equation
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\n" ); document.write( "Graphing you can see this is true also:
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-2%2C+8%2C+-2%2C+6%2C+2%2Fx%2C+%287%2F3%29-%28x%2F3%29%29+\"
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\n" ); document.write( "you can see they intersect and 6,(1/3) and 1,2
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\n" ); document.write( "Did this help you understand this stuff? \n" ); document.write( "
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