asked 85.9k views
5 votes
suppose you want to make an open topped box out of 4x6 index card by cutting a square out of each corner and then folding the edges. how large a square should you cut out of each corner in order to maximize the volume of the resulting box

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User Tubbe
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8.4k points

2 Answers

5 votes

Final answer:

To maximize the volume of an open-topped box from an index card, you need to use calculus to find the optimal size of the square to cut from each corner. The volume function V = x(4-2x)(6-2x) should be optimized by taking its derivative and finding the critical points where the derivative equals zero.

Step-by-step explanation:

To maximize the volume of an open-topped box created from a 4x6 index card by cutting out squares from each corner, we must define a variable for the square cut out. Let the side of the square cut from each corner be x. The new dimensions of the box will be (4-2x) by (6-2x) with a height of x. The volume V of the box is then given by V = x(4-2x)(6-2x).

To find the value of x that maximizes volume, we would take the derivative of the volume function with respect to x and set it to zero. Finding the critical points will let us know the value of x that gives the maximum volume. To solve this optimization problem, we use calculus methods. Unfortunately, without the precise calculations this answer will not be complete.

answered
User Alien
by
8.4k points
4 votes
so check the picture below

notice, since you're cutting out a square, the sides must all be equal, thus the largest "x" can't be 2, half of 4, it has to be just less than 2 or it has no volume, so x<2, and can't be 0, because, you'd have no volume either, so x>0, so 0<x<2


\bf V=(4-2x)(x)(6-2x)\implies V=(4x-2x^2)(6-2x) \\\\\\ V=4x^3-20x^2+24x \\\\\\ \cfrac{dv}{dx}=12x^2-40x+24\implies 0=12x^2-40x+24 \\\\\\ 0=3x^2-10x+6

anyway... so that'd be dv/dx... you can just run it through the quadratic formula to get the critical points, and run a first-derivative test on them, bearing in mind the range for "x", (0, 2)
suppose you want to make an open topped box out of 4x6 index card by cutting a square-example-1
answered
User Redorav
by
8.5k points
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