SOLUTION: a child care center has 200 feet of fencing to enclose two adjacent rectangular safe play areas (with one fencing in the adjacent side) a)write total area of the play areas as a

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Question 1068827: a child care center has 200 feet of fencing to enclose two adjacent rectangular safe play areas (with one fencing in the adjacent side)
a)write total area of the play areas as a function of x
b)write the area function in standard form to find algebraically the dimensions that will produce the maximum enclosed area.
please help with my question! thank you!

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +W+ = width ( 3 equal sizes )
Let +L+ = length ( 2 equal sizes )
+200+=+3W+%2B+2L+
+2L+=+200+-+3W+
+L+=+100+-+%283%2F2%29%2AW+
---------------------------
(a)
Let +A+ = the total area
+A+=+W%2AL+
+A+=+W%2A%28+100+-+%283%2F2%29%2AW+%29+
+A+=+-%283%2F2%29%2AW%5E2+%2B+100W+
----------------------------
(b)
This is a parabola with a maximum due
to the minus sign.
The W-value of the function maximum is:
+W%5Bmax%5D+=+-b%2F%282a%29+
+W%5Bmax%5D+=+%28-100%29%2F%282%2A%28-3%2F2%29+%29+
+W%5Bmax%5D+=+100%2F3+
and
+L%5Bmax%5D+=+100+-+%283%2F2%29%2AW+
+L%5Bmax%5D+=+100+-+%283%2F2%29%2A%28100%2F3%29+
+L%5Bmax%5D+=+100+-+50+
+L%5Bmax%5D+=+50+
----------------------------
The lengths that give the maximum area are:
+W+=+33.333%0D%0A%7B%7B%7B+L+=+50+
-----------------
check:
+200+=+3W+%2B+2L+
+200+=+3%2A33.333+%2B+2%2A50+
+200+=+100+%2B+100+
and
+A+=+W%2AL+
+A+=+33.333%2A50+
+A+=+1666.667+
( note that you can replace +W+ with +x+ and
+A+ with +y+, and that will give +y+=+f%28x%29+
the way they want. )
Here's the plot of +A+=+f%28W%29+
+graph%28+400%2C+400%2C+-10%2C+100%2C+-200%2C+2000%2C+-%283%2F2%29%2Ax%5E2+%2B+100x+%29+