Page 113 - How To Solve Word Problems In Calculus
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y + 4
4
y
2 x 2 x + 8
4
Step2
We wish to minimize the outer rectangular area of the
poster.
A = (x + 8)(y + 4)
= xy + 8y + 4x + 32
Step3
Since the inner rectangle must have an area of 50 in 2
xy = 50
50
y =
x
The area to be minimized may be expressed as a function of x.
50
A(x) = 50 + 8 + 4x + 32 0 < x < ∞
x
= 82 + 400x −1 + 4x
Step4
A (x) =−400x −2 + 4
400
0 =− + 4
x 2
100
