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2. A moving company supplies packing boxes for its customers. The dimensions of the box in terms of its widthare shown. The volume of the box is 4860 cubic inches.(w+12) in1Ewin.(27-w) ina. Write a polynomial equation that you can use to solve for the dimensions of the box.b. Solve the equation in part (a).c. What are the possible dimensions of the box?d. Which set of dimensions from part (c) do you prefer? Explain your reasoning.

User Swabygw
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1 Answer

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a. The shape of the box is a cuboid.

Mathematicaly, the volume of a cuboid is L * B * H

With respect to the given dimensions in the question, the volume of the box would be;

w * ( w + 12) * (27-w)

Since we have the value of the volume already, we can simply expand the brackets and equate to the given volume.

Hence;

w(w + 12)(27-w) = 4860

w( w(27-w) +12(27-w)) = 4860

w(27w - w^2 + 324 -12w) = 4860

w(27w -12w + 324 - w^2) = 4860

w(15w + 324 - w^2) = 4860

Thus, we have ;

15w^2 + 324w - w^3 = 4860

So the polynomial equation that can be used to get the dimension of the box is ;


15w^2+324w-w^{3\text{ }}\text{ = 4860}

b. We want to solve the equation above

15w^2 + 324w - w^3 = 4860

We solve the equation so as to get the values of w

Kindly note that because the polynomial equation is cubic, we shall be expecting three answers;

Thus, we proceed as follows;

Let us express the polynomial in the normal form as follows

-w^3 + 15w^2 + 324w - 4860 = 0

Let us now factorize;

-w^2( w -15) + 324( w - 15) = 0

(w - 15)( -w^2 + 324) = 0

Thus;

w-15 = 0 or 324 - w^2 = 0

Hence, w = 15 or w^2 = 324

So w = 15 or w = √324

w = 15 or ± 18

So the values of w are 15 , 18 or -18

c. The possible dimensions

We simply substite the value of w at each of the sides

The sides are ; w, 27-w and w + 12

at w = 15, we have

15 , 27-15 and 15 + 12 = 15, 12 and 27

At w = 18, we have

18, 27-18 and 18 + 12

18, 9 and 30

Lastly, we have w = -18

so we have ;

-18 , 27-(-18) and -18 + 12

-18, 45 and -6

d. Which set of dimensions is preferred

The dimension set 1 and 2 are preferred

i.e 18, 9 and 30 or 15,12 and 27

This is becasuse the last set of dimensions is not possible because the dimensions of a cuboid cannot be negative

User Saher Ahwal
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