document.write( "Question 118426: An open box is to be made from a 10 cm by 20 cm rectangular piece of cardboard by cutting a square from each corner and folding up the sides. The area of the bottom of the box is 96 cm squared. What is the length of the sides of the squares that are cut from the corners?\r
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Algebra.Com's Answer #86551 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
If you draw a picture, you can see that the dimensions of the bottom of the box are \"20-2x\" by \"10-2x\"\r
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\n" ); document.write( "\n" ); document.write( "So the area of the bottom is \"A=%2820-2x%29%2810-2x%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"96=%2820-2x%29%2810-2x%29\" Now plug in the given area \"A=96\"\r
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\n" ); document.write( "\n" ); document.write( "\"96=200-60x%2B4x%5E2\" Foil\r
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\n" ); document.write( "\n" ); document.write( "\"0=200-60x%2B4x%5E2-96\" Subtract 96 from both sides\r
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\n" ); document.write( "\n" ); document.write( "\"0=104-60x%2B4x%5E2\" Combine like terms\r
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\n" ); document.write( "\n" ); document.write( "\"0=4x%5E2-60x%2B104\" Rearrange the terms\r
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\n" ); document.write( "\n" ); document.write( "Let's use the quadratic formula to solve for x:\r
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\n" ); document.write( "\n" ); document.write( "Starting with the general quadratic\r
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\n" ); document.write( "\n" ); document.write( "\"ax%5E2%2Bbx%2Bc=0\"\r
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\n" ); document.write( "\n" ); document.write( "the general solution using the quadratic equation is:\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29\"\r
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\n" ); document.write( "\n" ); document.write( "So lets solve \"4%2Ax%5E2-60%2Ax%2B104=0\" ( notice \"a=4\", \"b=-60\", and \"c=104\")\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28--60+%2B-+sqrt%28+%28-60%29%5E2-4%2A4%2A104+%29%29%2F%282%2A4%29\" Plug in a=4, b=-60, and c=104\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2860+%2B-+sqrt%28+%28-60%29%5E2-4%2A4%2A104+%29%29%2F%282%2A4%29\" Negate -60 to get 60\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2860+%2B-+sqrt%28+3600-4%2A4%2A104+%29%29%2F%282%2A4%29\" Square -60 to get 3600 (note: remember when you square -60, you must square the negative as well. This is because \"%28-60%29%5E2=-60%2A-60=3600\".)\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2860+%2B-+sqrt%28+3600%2B-1664+%29%29%2F%282%2A4%29\" Multiply \"-4%2A104%2A4\" to get \"-1664\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2860+%2B-+sqrt%28+1936+%29%29%2F%282%2A4%29\" Combine like terms in the radicand (everything under the square root)\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2860+%2B-+44%29%2F%282%2A4%29\" Simplify the square root (note: If you need help with simplifying the square root, check out this solver)\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2860+%2B-+44%29%2F8\" Multiply 2 and 4 to get 8\r
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\n" ); document.write( "\n" ); document.write( "So now the expression breaks down into two parts\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2860+%2B+44%29%2F8\" or \"x+=+%2860+-+44%29%2F8\"\r
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\n" ); document.write( "\n" ); document.write( "Lets look at the first part:\r
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\n" ); document.write( "\n" ); document.write( "\"x=%2860+%2B+44%29%2F8\"\r
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\n" ); document.write( "\n" ); document.write( "\"x=104%2F8\" Add the terms in the numerator\r
\n" ); document.write( "\n" ); document.write( "\"x=13\" Divide\r
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\n" ); document.write( "\n" ); document.write( "So one answer is\r
\n" ); document.write( "\n" ); document.write( "\"x=13\"\r
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\n" ); document.write( "\n" ); document.write( "Now lets look at the second part:\r
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\n" ); document.write( "\n" ); document.write( "\"x=%2860+-+44%29%2F8\"\r
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\n" ); document.write( "\n" ); document.write( "\"x=16%2F8\" Subtract the terms in the numerator\r
\n" ); document.write( "\n" ); document.write( "\"x=2\" Divide\r
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\n" ); document.write( "\n" ); document.write( "So another answer is\r
\n" ); document.write( "\n" ); document.write( "\"x=2\"\r
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\n" ); document.write( "\n" ); document.write( "So our possible solutions are:\r
\n" ); document.write( "\n" ); document.write( "\"x=13\" or \"x=2\"\r
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\n" ); document.write( "\n" ); document.write( "However, since 13 is greater than 10, the solution \"x=13\" is not possible since the square cutout cannot have a longer length than one of the sides.\r
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\n" ); document.write( "\n" ); document.write( "So our only solution is \"x=2\"\r
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\n" ); document.write( "\n" ); document.write( "Check:\r
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\n" ); document.write( "\n" ); document.write( "Remember, the area is\r
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\n" ); document.write( "\n" ); document.write( "\"A=%2820-2x%29%2810-2x%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"96=%2820-2%282%29%29%2810-2%282%29%29\" Plug in the given area \"A=96\" and \"x=2\"\r
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\n" ); document.write( "\n" ); document.write( "\"96=%2820-4%29%2810-4%29\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"96=%2816%29%286%29\" Subtract\r
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\n" ); document.write( "\n" ); document.write( "\"96=96\" Multiply. Since the two sides of the equation are equal, this verifies our answer.
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