Use the discriminant to determine the number and type of solutions the equation has.
2 answers:
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Answer:
The width of the computer compartment is 9 inches
The length of the computer compartment is 33 inches
The height of the computer compartment is 27 inches
Step-by-step explanation:
The given data on the rectangular prism compartment are;
The volume of the rectangular prism, V = 8019 cubic inches
The length of the compartment, l = 24 inches + The width, w
The height of the compartment, h = 18 inches + The width, w
Therefore, we have;
l = 24 + w
h = 18 + w
V = l × h × w
∴ V = (24 + w) × (18 + w) × w = w³ + 42·w² + 432·w = 8019
w³ + 42·w² + 432·w - 8019 = 0
By graphing the above function with MS Excel, we have one of the solution is w = 9
∴ (w - 9) is a factor of w³ + 42·w² + 432·w - 8019 = 0
Dividing, we get;
w² + 51·w + 891
w³ + 42·w² + 432·w - 8019 = 0
w³ - 9·w²
51·w² - 459·w
891·w
891·w + 8019
0
Therefore,
w³ + 42·w² + 432·w - 8019 = 0
w³ + 42·w² + 432·w - 8019 = (x - 9)·(w² + 51·w + 891) = 0
The determinant of the factor, w² + 51·w + 891 = 51² - 4×1×891 = -963, therefore, the it has complex roots
Therefore, the real solution of (x - 9)·(w² + 51·w + 891) = 0 is w = 9
The width of the computer compartment, w = 9 inches
The length of the computer compartment, l = 24 inches + 9 inches = 33 inches
The height of the computer compartment, h = 18 inches + 9 inches = 27 inches.
Lets say that the two unknown integers are 
and 
.
We know the following things about and :
And, we want to find
.
To solve this, we'll use the expansion of the squared of the sum of any two inegers; this is expressed as:
So, given what we know about the unknown integers, the previous can be written as:
We can easily solve for:
The answer is 168.
Another approach to solve the problem is, from the two starting equations, compute the values of and , which are 12 and 14, and directly compute their product; however, the approach described is more elegant.
We know the following things about
And, we want to find
To solve this, we'll use the expansion of the squared of the sum of any two inegers; this is expressed as:
So, given what we know about the unknown integers, the previous can be written as:
We can easily solve for
The answer is 168.
Another approach to solve the problem is, from the two starting equations, compute the values of