Question
A truck rental company rents a 12 ft by 8 ft by 6 ft truck for
per day plus mileage. A customer prefers to rent a
less expensive smaller truck whose dimensions are
smaller on each side. If the volume of the smaller truck is
, determine the dimensions of the smaller truck.
less expensive smaller truck whose dimensions are
Ask by Tucker Mills. in the United States
Mar 16,2025
Upstudy AI Solution
Tutor-Verified Answer
Answer
The smaller truck has dimensions of 10 ft by 6 ft by 4 ft.
Solution
We are given that the original truck has dimensions
,
, and
and that the smaller truck’s dimensions are reduced by
feet on each side. Thus, the dimensions of the smaller truck are
The volume of the smaller truck is given as
Step 1. Form the Volume Equation
Step 2. Expand the Equation
First, multiply the first two factors:
Now multiply this result by the third factor
:
Expand each term:
Combine the like terms:
So the equation becomes:
Step 3. Rearrange the Equation
Subtract 240 from both sides:
which simplifies to:
Multiply the entire equation by
to make the leading coefficient positive:
Step 4. Factor the Cubic Equation
We look for a rational root. Testing
:
Thus,
is a root, and we can factor the cubic as:
Step 5. Find the Real Solution
The quadratic factor is
Calculate the discriminant:
Since the discriminant is negative, there are no additional real roots.
Thus, the only real solution is:
Step 6. Determine the Dimensions of the Smaller Truck
Substitute
into the dimensions:
Therefore, the dimensions of the smaller truck are:
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Bonus Knowledge
To find the dimensions of the smaller truck, we start by calculating the volume of the larger truck. The volume
of a rectangular prism is given by
.
For the larger truck:
Now, if the dimensions of the smaller truck are
ft,
ft, and
ft, we can set up the equation based on the volume of the smaller truck provided as
:
Expanding the left side can be a bit tricky, but let’s go step by step. Firstly, we can find the factor
:
Next, we multiply this by
:
Now we will set this equal to
:
Rearranging gives us:
Multiplying new by -1 to simplify factors out:
We can use synthetic division or numerical methods to find the roots. However, through trial and error or calculator assistance, we find one root to be
:
Substituting back into the equation,
Substituting back into the equation,
The smaller truck dimensions are thus:
which gives us dimensions of
, which is incorrect since dimensions cannot be zero.
This indicates found is too large: retry small values of
, where feasible
or
.
This indicates
For instance, trying x = 2:
Thus, the real dimensions of the smaller truck are: