document.write( "Question 283963: An engineer is designing a rectangular computer screen to have an
\n" ); document.write( "area of 150 square inches and a diagonal of 18 inches. Which of the
\n" ); document.write( "following equations could the engineer solve to find the value of x,
\n" ); document.write( "the length of a side of the screen?
\n" ); document.write( "A. x2 – 18x + 150 = 0
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\n" ); document.write( "B. x2 – 324x + 22,500 = 0
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\n" ); document.write( "C. x4 – 324x2 + 22,500 = 0
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\n" ); document.write( "D. x4 + 324x2 – 22,500 = 0
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Algebra.Com's Answer #206093 by Edwin McCravy(20086)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "The diagonal, which is 18 inches is the hypotenuse of\r\n" );
document.write( "the right triangle with legs x and y. Using the\r\n" );
document.write( "Pythagorean theorem, we have the equation:\r\n" );
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document.write( "\"x%5E2%2By%5E2=18%5E2\"\r\n" );
document.write( "\"x%5E2%2By%5E2=324\" \r\n" );
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document.write( "The area of the whole rectangle given as 150 square inches \r\n" );
document.write( "is the length x times the width y.  So we have the \r\n" );
document.write( "equation:\r\n" );
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document.write( "\"xy=150\"\r\n" );
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document.write( "So we have the system:\r\n" );
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document.write( "\"system%28x%5E2%2By%5E2=324%2Cxy=150%29\"\r\n" );
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document.write( "Solve the second equation for y\r\n" );
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document.write( "\"xy=150\"\r\n" );
document.write( "\"y=150%2Fx\"\r\n" );
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document.write( "Now we substitute \"150%2Fx\" for \"y\" in the\r\n" );
document.write( "equation:\r\n" );
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document.write( "\"x%5E2%2By%5E2=324\"\r\n" );
document.write( "\"x%5E2%2B%28150%2Fx%29%5E2=324\"\r\n" );
document.write( "\"x%5E2%2B150%5E2%2Fx%5E2=324\"\r\n" );
document.write( "\"x%5E2%2B22500%2Fx%5E2=324\"\r\n" );
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document.write( "Multiply through by \"x%5E2\" to clear of fractions:\r\n" );
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document.write( "\"x%5E4%2B22500=324x%5E2\"\r\n" );
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document.write( "Get 0 on the right by subtracting \"324x%5E2\" from\r\n" );
document.write( "both sides:\r\n" );
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document.write( "\"x%5E4%2B22500-324x%5E2=0\"\r\n" );
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document.write( "Get it in descending order:\r\n" );
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document.write( "\"x%5E4-324x%5E2%2B22500=0\"\r\n" );
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document.write( "That is choice (C).\r\n" );
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document.write( "Edwin

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