document.write( "Question 1189165: Dear Colleagues\r
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document.write( "I have the following question to find a solution to:
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document.write( "The length of a rectangle exceeds its breadth by 4 centimetres. If the length were halved and the breadth increased by 5 centimetres, the area would be decreased by 35 square centimetres. Find the length of the rectangle.\r
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document.write( "I do not know if I can draw in this website, but whilst trying to find the solutions, I drew 2 rectangles: the one on the left had the dimensions (x)(x+4) for width and length respectively, the one on the right had dimensions ((x+4)/2)(x+5) for length and width respectively.
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document.write( "The question then reads - for me - [((x+4)/2)(x+5)] - 35 = x(x+4)
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document.write( "Multiplying the left hand by 2 to clear the fraction, we get
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document.write( "[(x+4)(2x+10)]-35 = x(x+4)
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document.write( "and after multiplying out we get
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document.write( "[2x^2+10x+8x+40]-35 = x^2+4x
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document.write( "Collecting like terms gives us
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document.write( "2x^2+18x+5 = x^2+4x
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document.write( "which simplifies to
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document.write( "x^2+14x+5=0
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document.write( "We cannot factorise, so using the quadratic formula we get
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document.write( "a = 1, b= 14, c = 5
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document.write( "and putting all of this into the formula we get\r
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document.write( "x = (-b+/- sqrt of b^2-4ac)/2
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document.write( "which gives
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document.write( "x = (-14 +/- sqrt (14)^2-(4)(1)(5))/2\r
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document.write( "which gives us, finally, x = (-14 +/-13.23)/2\r
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document.write( "I am assuming that we need a real number for the length of the side of the rectangle, so do not wish to get into imaginary numbers...
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document.write( "Where have I gone wrong? \n" );
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Algebra.Com's Answer #820429 by Theo(13342)![]() ![]() You can put this solution on YOUR website! i did it my way and i think i got the right answer. \n" ); document.write( "see my worksheet below:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " ![]() \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "looking at the way you did it, i think i know where you went wrong.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "here's my worksheets about the way you did it.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " ![]() \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " ![]() \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "let me know if you have any questions.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "theo\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |