document.write( "Question 833912: Help! Don't know how to put story problem into quadratic formula:\r
\n" ); document.write( "\n" ); document.write( "A rectangular garden is 30 ft by 40 ft. Part of the garden is removed in order to install a walkway of uniform width around it. The area of the new garden is one-half the area of the old garden. How wide is the walkway?
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Algebra.Com's Answer #502756 by MathLover1(20850)\"\" \"About 
You can put this solution on YOUR website!
A rectangular garden is 30 ft by 40 ft. Part of the garden is removed in order to install a walkway of uniform width around it. The area of the new garden is one-half the area of the old garden. How wide is the walkway?\r
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\n" ); document.write( "\n" ); document.write( "Area of the entire garden is \"A=+30ft+%2A+40ft+=+1200ft%5E2\"\r
\n" ); document.write( "\n" ); document.write( "Let \"x\" be the width of the walkway.\r
\n" ); document.write( "\n" ); document.write( "Length of the reduced garden is \"L=+%2840+-+2x%29ft\"
\n" ); document.write( "Width of the reduced garden is \"+W=+%2830+-+2x%29ft\"\r
\n" ); document.write( "\n" ); document.write( "Area of the reduced garden is \"A%5Br%5D+=+%2840+-+2x%29+%2A+%2830+-+2x%29ft%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "Area of the reduced garden is one-half the area of the old garden; so, we have
\n" ); document.write( "\"A%5Br%5D+=A%2F2\" or
\n" ); document.write( "\"2A%5Br%5D+=A\"
\n" ); document.write( "since
\n" ); document.write( "\"A%5Br%5D+=+%2840+-+2x%29+%2A+%2830+-+2x%29ft%5E2\" and \"A=+1200ft%5E2\", we have\r
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\n" ); document.write( "\n" ); document.write( "\"2%2840+-+2x%29+%2A+%2830+-+2x%29ft%5E2=1200ft%5E2\"...simplify\r
\n" ); document.write( "\n" ); document.write( "\"%2840+-+2x%29+%2A+%2830+-+2x%29=600\"....expand\r
\n" ); document.write( "\n" ); document.write( "\"120+-80x-+60x+%2B+4x%5E2=600\"\r
\n" ); document.write( "\n" ); document.write( "\"+4x%5E2-140x%2B1200=600\"\r
\n" ); document.write( "\n" ); document.write( "\"+4x%5E2-140x%2B1200-600=0\"\r
\n" ); document.write( "\n" ); document.write( "\"+4x%5E2-140x-600=0\"...both sides divide by \"4\"\r
\n" ); document.write( "\n" ); document.write( "\"+x%5E2-35x-150=0\"......solve for \"x\"\r
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Solved by pluggable solver: Quadratic Formula
Let's use the quadratic formula to solve for x:

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\n" ); document.write( " Starting with the general quadratic
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\n" ); document.write( " \"ax%5E2%2Bbx%2Bc=0\"
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\n" ); document.write( " the general solution using the quadratic equation is:
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\n" ); document.write( " \"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29\"
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\n" ); document.write( " So lets solve \"4%2Ax%5E2-140%2Ax%2B600=0\" ( notice \"a=4\", \"b=-140\", and \"c=600\")
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\n" ); document.write( " \"x+=+%28--140+%2B-+sqrt%28+%28-140%29%5E2-4%2A4%2A600+%29%29%2F%282%2A4%29\" Plug in a=4, b=-140, and c=600
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\n" ); document.write( " \"x+=+%28140+%2B-+sqrt%28+%28-140%29%5E2-4%2A4%2A600+%29%29%2F%282%2A4%29\" Negate -140 to get 140
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\n" ); document.write( " \"x+=+%28140+%2B-+sqrt%28+19600-4%2A4%2A600+%29%29%2F%282%2A4%29\" Square -140 to get 19600 (note: remember when you square -140, you must square the negative as well. This is because \"%28-140%29%5E2=-140%2A-140=19600\".)
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\n" ); document.write( " \"x+=+%28140+%2B-+sqrt%28+19600%2B-9600+%29%29%2F%282%2A4%29\" Multiply \"-4%2A600%2A4\" to get \"-9600\"
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\n" ); document.write( " \"x+=+%28140+%2B-+sqrt%28+10000+%29%29%2F%282%2A4%29\" Combine like terms in the radicand (everything under the square root)
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\n" ); document.write( " \"x+=+%28140+%2B-+100%29%2F%282%2A4%29\" Simplify the square root (note: If you need help with simplifying the square root, check out this solver)
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\n" ); document.write( " \"x+=+%28140+%2B-+100%29%2F8\" Multiply 2 and 4 to get 8
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\n" ); document.write( " So now the expression breaks down into two parts
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\n" ); document.write( " \"x+=+%28140+%2B+100%29%2F8\" or \"x+=+%28140+-+100%29%2F8\"
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\n" ); document.write( " Lets look at the first part:
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\n" ); document.write( " \"x=%28140+%2B+100%29%2F8\"
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\n" ); document.write( " \"x=240%2F8\" Add the terms in the numerator
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\n" ); document.write( " \"x=30\" Divide
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\n" ); document.write( " So one answer is
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\n" ); document.write( " \"x=30\"
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\n" ); document.write( " Now lets look at the second part:
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\n" ); document.write( " \"x=%28140+-+100%29%2F8\"
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\n" ); document.write( " \"x=40%2F8\" Subtract the terms in the numerator
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\n" ); document.write( " \"x=5\" Divide
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\n" ); document.write( " So another answer is
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\n" ); document.write( " \"x=5\"
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\n" ); document.write( " So our solutions are:
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\n" ); document.write( " \"x=30\" or \"x=5\"
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\n" ); document.write( "\n" ); document.write( "If \"x+=+5\", the length is \"L=+%2840+-+2%2A5%29+=40-+10=30\" \r
\n" ); document.write( "\n" ); document.write( "and width \"W=+%2830+-+2%2A5%29+=30-10=20\"\r
\n" ); document.write( "\n" ); document.write( "If \"x+=+30\", the length is \"L=+%2840+-+2%2A30%29+=40-+60=-20\" \r
\n" ); document.write( "\n" ); document.write( "and width \"W=+%2830+-+2%2A30%29+=+-30\"\r
\n" ); document.write( "\n" ); document.write( "So, the second case (\"x+=+30\") is ruled out because you can't have a width and a length equal to negative number.\r
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\n" ); document.write( "\n" ); document.write( "so the walkway is \"x=5ft\" wide
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