document.write( "Question 572611: The length of a rectangle is 2 feet more than 3 times the width. If the area is 16 square feet, find the width and the length. \n" ); document.write( "
Algebra.Com's Answer #368616 by mathsmiles(68)![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "Let's write down everything we know: \n" ); document.write( "L = 2 + 3W (length is 2 feet more than 3 times the width) \n" ); document.write( "A is 16 sq ft \n" ); document.write( "A = L x W\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If we substitute in the area formula so we only have one variable, W: \n" ); document.write( "L x W = 16 \n" ); document.write( "(2+3W) x W = 16 Multiplying out the paren \n" ); document.write( "2W + 3W^2 = 16 \n" ); document.write( "Let's rearrange the terms: \n" ); document.write( "3W^2 + 2W = 16 \n" ); document.write( "Subtracting 16 from each side: \n" ); document.write( "3W^2 + 2W - 16 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now we factor this: \n" ); document.write( "(3W _ _) (W _ _) = 0 Where we have to figure out the operators and terms \n" ); document.write( "What are factors of 16 that we can try? \n" ); document.write( "16 = 4x4 \n" ); document.write( "16 = 8x2 (oh good, there's only 2)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's try the 2 4s: \n" ); document.write( "(3W _ 4)(W _ 4) = 0 \n" ); document.write( "Since 16 is negative, one must be positive, the other negative: \n" ); document.write( "Try: \n" ); document.write( "(3W - 4)(W + 4) = 3W^2 + 12W - 4W -16 (12-4 is not 2 so this isn't it) \n" ); document.write( "Try: \n" ); document.write( "(3W - 2)(W + 8) = 3W^2 + 24W - 2W -16 (24-2 is not 2 so let's switch the 2 & 8 and try this one again) \n" ); document.write( "(3W - 8)(W + 2) = 3W^2 + 6W - 8W - 16 (6-8 is neg 2 so let's switch the signs) \n" ); document.write( "(3W + 8)(W - 2) = 3W^2 -6W + 8W -16 \n" ); document.write( "= 3W^2 + 2W -16 Yay! \n" ); document.write( "Writing it again so we can finish: \n" ); document.write( "(3W + 8)(W-2) = 0 \n" ); document.write( "3W + 8 = 0 Subtract 8 from both sides: \n" ); document.write( "3W = -8 Divide both sides by 3 \n" ); document.write( "W = -8/3 (not likely since this is a rectangle that the width is negative) \n" ); document.write( "W - 2 = 0 Add 2 to both sides \n" ); document.write( "W = 2 Aha!\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now we need to figure the length: \n" ); document.write( "L = 2+3xW \n" ); document.write( "L = 2+3(2) \n" ); document.write( "L = 2+6 \n" ); document.write( "L = 8\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Checking: \n" ); document.write( "A = L x W \n" ); document.write( "A = 8 x 2 \n" ); document.write( "16 = 16 Correct!\r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |