document.write( "Question 866123: a rectangle has a length that is 5 less than twice the width.if the rectangle has an area of 63, find the length and width.
\n" ); document.write( "I am having trouble figuring out how to set up this problem I would be very grateful if someone could help me.
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Algebra.Com's Answer #522109 by KMST(5328)\"\" \"About 
You can put this solution on YOUR website!
\"w\"= width of the rectangle (in whatever units of length they use)
\n" ); document.write( "\"2w\"= twice the width
\n" ); document.write( "\"2w-5\"= length of the rectangle (it is 5 less than twice the width)
\n" ); document.write( "The area of the rectangle is length times width, so it is
\n" ); document.write( "\"%282w-5%29w=63\"
\n" ); document.write( "That is the equation to solve, but we re-arrange it.
\n" ); document.write( "\"%282w-5%29w=63\"
\n" ); document.write( "\"2w%5E2-5w=63\"
\n" ); document.write( "\"2w%5E2-5w-63=0\"
\n" ); document.write( "Now it looks like a standard \"ax%5E2%2Bbx%2Bc=0\" quadratic equation and we can solve it using the quadratic formula:
\n" ); document.write( "\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\" ,
\n" ); document.write( "except that instead of \"x\" we have \"w\" , and we have
\n" ); document.write( "\"a=2\" , \"b=-5\" , and \"c=-63\" , so
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\n" ); document.write( "The two solutions for \"2w%5E2-5w-63=0\" are
\n" ); document.write( "\"w=%285+%2B+23%29%2F4=28%2F4=highlight%287%29\" and
\n" ); document.write( "(5 - 23)/4=-18/4=-9/2}}} ,
\n" ); document.write( "but since the width of the rectangle must be a positive number,
\n" ); document.write( "we must discard \"w=-9%2F2\" , and the solution is
\n" ); document.write( "\"highlight%28w=7%29\" , along with
\n" ); document.write( "\"length=2w-5=2%2A7-5=14-5=highlight%289%29\"
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\n" ); document.write( "The same \"2w%5E2-5w-63=0\" quadratic equation can be solved by other means.
\n" ); document.write( "Ypu could \"complete the square\" (not so easy),
\n" ); document.write( "or you could solve it by factoring \"2w%5E2-5w-63\" (if you are good at factoring).
\n" ); document.write( "Factoring:
\n" ); document.write( "\"2w%5E2-5w-63=%282w%5E2-14w%29%2B%289w-63%29=2w%28w-7%29%2B9%28w-7%29=%282w%2B9%29%28w-7%29\"
\n" ); document.write( "so \"2w%5E2-5w-63=0\" can be written as \"%282w%2B9%29%28w-7%29=0\" ,
\n" ); document.write( "which is true if \"system%282w%2B9=0%2C%22or%22%2Cw-7=0%29\" ,
\n" ); document.write( "and those two options lead us to the solutions
\n" ); document.write( "\"w=-9%2F2%2C+%22or%22%2C+w=7%29\" found above.
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\n" ); document.write( "Completing the square:
\n" ); document.write( "\"2w%5E2-5w-63=0\"<-->\"2w%5E2-5w=63\"
\n" ); document.write( "dividing both sides of the equal sign by 2,
\n" ); document.write( "\"w%5E2-%285%2F2%29w=63%2F2\"
\n" ); document.write( "\"w%5E2-%285%2F2%29w%2B%285%2F4%29%5E2=63%2F2%2B%285%2F4%29%5E2\"
\n" ); document.write( "\"%28w-5%2F4%29%5E2=63%2F2%2B25%2F16\"
\n" ); document.write( "\"%28w-5%2F4%29%5E2=504%2F16%2B25%2F16\"
\n" ); document.write( "\"%28w-5%2F4%29%5E2=529%2F16\"
\n" ); document.write( "So
\n" ); document.write( "which means that
\n" ); document.write( "\"system%28w=23%2F4%2B5%2F4=28%2F4=7%2C%22or%22%2Cw=-23%2F4%2B5%2F4=-18%2F4=-9%2F2%29\"
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