SOLUTION: The length of a rectangular swimming pool is twice its width. The pool is surrounded by a walk that is 2 feet wide. The area of the region consisting of the pool and the walk is 10

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Question 1030133: The length of a rectangular swimming pool is twice its width. The pool is surrounded by a walk that is 2 feet wide. The area of the region consisting of the pool and the walk is 1056 square feet.
(a) Use the method of completing the square to determine the dimensions of the swimming pool.
The length of the pool is ____ feet, and the width of the pool is ____feet.
(b) If the material for the walk costs $8 per square foot, how much would the material cost for the entire walk?
The material would cost $____ .

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +w+ = the width of the pool
+2w+ = the length of the pool
There is 2 ft of walkway on BOTH sides of
the pool, so add +4+ ft to both width and length
+1056+=+%28+w+%2B+4+%29%2A%28+2w+%2B+4+%29+
+2w%5E2+%2B+8w+%2B+4w+%2B+16+=+1056+
+2w%5E2+%2B+12w+%2B+16+=+1056+
+2w%5E2+%2B+12w+=+1040+
+w%5E2+%2B+6w+=+520+
Complete the square:
+w%5E2+%2B+6w+%2B+%28+6%2F2+%29%5E2+=+520+%2B+%28+6%2F2+%29%5E2+
+w%5E2+%2B+6w+%2B+9+=+520+%2B+9+
+%28+w+%2B+3+%29%5E2+=+529+
+%28+w+%2B+3+%29%5E2+=+23%5E2+
+w+%2B+3+=+23+
+w+=+20+
and
+2w+=+40+
(a)
The length is 40 ft
The width is 20 ft
-------------------
(b)
The area of the walkway is:
+1056+-+w%2A%282w%29+
+1056+-+20%2A40+
+1056+-+800+=+256+ ft2
and
+256%2A8+=+2048+
The material costs $2,048
-----------------------
check:
++%28+w+%2B+4+%29%2A%28+2w+%2B+4+%29+=+1056+
+%28+20+%2B+4+%29%2A%28+2%2A20+%2B+4+%29+=+1056+
+24%2A44+=+1056+
+1056+=+1056+
OK