document.write( "Question 351137: This is a mathematics problem which one of my cousin asked me yesterday. He is in grade 4. However, I cannot help him because I am not good in maths.\r
\n" ); document.write( "\n" ); document.write( "The width of a rectangle is 20 cm more than half the length.
\n" ); document.write( "Its area is 4800 sq.cm.
\n" ); document.write( "Find its width. \n" ); document.write( "
Algebra.Com's Answer #250977 by unlockmath(1688)\"\" \"About 
You can put this solution on YOUR website!
Hello,
\n" ); document.write( "Well, this seems a bit advanced for a 4th grader.
\n" ); document.write( "First we'll let x show one side and 1/2x+20 for the other side.
\n" ); document.write( "Now we can set up an equation:
\n" ); document.write( "x(1/2x+20)=4800
\n" ); document.write( "Expand this out to:
\n" ); document.write( "1/2x^2+20x=4800
\n" ); document.write( "Subtract 4800 from both sides to get:
\n" ); document.write( "1/2x^2+20x-4800=0
\n" ); document.write( "Multiply by 2 to get rid of the fraction:
\n" ); document.write( "x^2+40x-9600=0
\n" ); document.write( "This can be factored as:
\n" ); document.write( "(x-80)(x+120)=0
\n" ); document.write( "solve for x to get:
\n" ); document.write( "x=80
\n" ); document.write( "x=-120
\n" ); document.write( "80 is the sensible answer, so the sides are
\n" ); document.write( "80 cm and 60 cm
\n" ); document.write( "This can be checked by multiplying these to get 4800 sq cm
\n" ); document.write( "Got it?
\n" ); document.write( "RJ
\n" ); document.write( "www.math-unlock.com\r
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