document.write( "Question 256781: If the length and width of a rectangle were each increased by 1, the area would be
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document.write( "84. The area would be 48 if the length and width were each diminished by 1.
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document.write( "Find the perimeter of the original rectangle. \n" );
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Algebra.Com's Answer #188826 by Theo(13342)![]() ![]() You can put this solution on YOUR website! let L = length and W = width.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "area = L*W\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(L+1)*(W+1) = 84\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(L-1)*(W-1) = 48\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "multiply these out to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "LW + L + W + 1 = 84 \n" ); document.write( "LW - L - W + 1 = 48\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "add both these equations together to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "2LW + 2 = 132\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "subtract 2 from both sides of these equations to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "2LW = 130\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "divide both sides of these equations by 2 to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "LW = 65\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "substitute for LW in the original 2 equations to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "LW + L + W + 1 = 84 \n" ); document.write( "LW - L - W + 1 = 48\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "become:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "65 + L + W + 1 = 84 \n" ); document.write( "65 - L - W + 1 = 48\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "subtract 66 from both sides of these equations to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "L + W = 18 \n" ); document.write( "-L -W = -18\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Solve for L in each equation to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "L = 18 - W (same answer for each equation).\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "You have a value for L in relation to W.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "substitute for L in the first original equation to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(L+1)*(W+1) = 84 becomes:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(18-W+1) * (W+1) = 84\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "simplify each factor to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(19-W) * (W + 1) = 84\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "multiply out the factors to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "19W + 19 - W^2 - W = 84\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "combine like terms to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-W^2 + 18W + 19 = 84\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "subtract 84 from both sides of the equation to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-W^2 + 18W - 65 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "multiply both sides of the equation by -1 to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "W^2 - 18W + 65 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "factor to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(W-13) * (W - 5) = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "W = 13 or W = 5\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "since L = 18 - W, then you also get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "When W = 13, L = 5 \n" ); document.write( "When W = 5, L = 13\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "substitute these values in the original equations to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "When W = 13 and L = 5, then:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(L+1)*(W+1) = 84 \n" ); document.write( "(L-1)*(W-1) = 48\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "become:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "6*14 = 84 \n" ); document.write( "4*12 = 48\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "When W = 5 and L = 13, then:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(L+1)*(W+1) = 84 \n" ); document.write( "(L-1)*(W-1) = 48\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "become:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "14*6 = 84 \n" ); document.write( "12*4 = 48\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "all equations are true so the values for L and W are good.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Perimeter = 2L + 2W.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "When L = 5 and W = 13, perimeter becomes 10 + 26 = 36\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "When L = 13 and W = 5, perimeter becomes 26 + 10 = 36\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your answer is:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "perimeter = 36\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( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |