document.write( "Question 564768: Lee has a rectangular plot to use for a flower garden. She plans to include a gravel
\n" ); document.write( "border of uniform width around the flower garden so visitors can walk completely around
\n" ); document.write( "the flowers to view them more easily. The total size of the garden and gravel border is to
\n" ); document.write( "be 15 feet by 21 feet. If Lee has enough gravel to cover 117 square feet for the border,
\n" ); document.write( "how wide will the gravel border be? What will the dimensions of the actual flower garden
\n" ); document.write( "be? Round answers to nearest tenth.
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Algebra.Com's Answer #365498 by Theo(13342)\"\" \"About 
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let x = the width of the border.
\n" ); document.write( "the total area including the border is equal to 315 square feet.
\n" ); document.write( "the area of the border is equal to 117 square feet.
\n" ); document.write( "subtract 117 from 315 and you get 198 square feet for the garden.
\n" ); document.write( "the length of the garden will be equal to 21 - 2x.
\n" ); document.write( "the width of the garden will be equal to 15 - 2x.
\n" ); document.write( "since the area of the garden is equal to the length times the width, then the equation for the area of the garden will be:
\n" ); document.write( "(21 - 2x) * (15 - 2x) = 198 square feet.
\n" ); document.write( "we multiply these factors out to get:
\n" ); document.write( "4x^2 - 72x + 315 = 198
\n" ); document.write( "we subtract 198 from both sides of this equation to get:
\n" ); document.write( "4x^2 - 72x + 117 = 0
\n" ); document.write( "this doesn't factor well so we use the quadratic formula to get:
\n" ); document.write( "x = 16.19374728 or x = 1.806252715
\n" ); document.write( "x = 16.19374728 doesn't work because 21 - 2*16 is negative.
\n" ); document.write( "the answer has to be x = 1.806252715 or there is no solution.
\n" ); document.write( "we go back to our equation for the area of the garden.
\n" ); document.write( "it is:
\n" ); document.write( "(21 - 2x) * (15 - 2x) = 198 square feet.
\n" ); document.write( "substituting 1.806252715 for x gets us:
\n" ); document.write( "21 - 2*1.806252715) * (15 - 2*1.806252715) = 198
\n" ); document.write( "simplifying this equation gets us:
\n" ); document.write( "17.38749457 * 11.38749457 = 198
\n" ); document.write( "simplifying this further gets:
\n" ); document.write( "198 = 198.
\n" ); document.write( "this confirms the value for x is good.
\n" ); document.write( "we confirm even further by determining the area of the border.
\n" ); document.write( "that will be:
\n" ); document.write( "4 * x^2 plus 2 *(21 - 2x) * x plus 2 * (15-2x) * x
\n" ); document.write( "substituting for x in this equation gets us 117 square feet.
\n" ); document.write( "the area of the garden is 198 square feet.
\n" ); document.write( "the area of the border is 117 square feet.
\n" ); document.write( "the value of x = 1.806252715 feet.
\n" ); document.write( "x is the width of the border.
\n" ); document.write( "the length of the garden will be 21 - 2x = = 17.38749457
\n" ); document.write( "the width of the garden will be 15 - 2x = 11.38749457
\n" ); document.write( "the area of the garden is equal to (21-2x) * (15-2x) = 198 square feet.
\n" ); document.write( "the equation we solved using the quadratic formula is:
\n" ); document.write( "4x^2 - 72x + 117 = 0
\n" ); document.write( "in that equation:
\n" ); document.write( "a = 4
\n" ); document.write( "b = -72
\n" ); document.write( "c = 117
\n" ); document.write( "the quadratic formula is:
\n" ); document.write( "x = \"%28-b+%2B-+sqrt%28b%5E2-4ac%29%29%2F%282a%29\"
\n" ); document.write( "your answer need to be to the nearest tenth of a foot.
\n" ); document.write( "that makes your answer:
\n" ); document.write( "the width of the border is equal to 1.8 feet.
\n" ); document.write( "the length of the garden is equal to 17.4 feet
\n" ); document.write( "the width of the garden is equal to 11.4 feet.\r
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