The volume of a rectangular prism is given by the formula [tex]V = lwh[/tex], where [tex]l[/tex] is the length of the prism, [tex]w[/tex] is the width, and [tex]h[/tex] is the height. Suppose a box in the shape of a rectangular prism has length [tex]\((2a+11)\)[/tex], width [tex]\((5a-12)\)[/tex], and height [tex]\((a+6)\)[/tex]. Which expression represents the volume of the box?

A. [tex]10a^3 + 22a^2 - 360a - 792[/tex]
B. [tex]10a^3 + 67a^2 - 90a - 792[/tex]
C. [tex]10a^3 + 139a^2 + 606a + 792[/tex]
D. [tex]10a^3 + 91a^2 + 54a - 792[/tex]



Answer :

To solve this problem, we're tasked with finding the volume of a rectangular prism given its length, width, and height as algebraic expressions. Let's proceed step-by-step:

1. Identify the given expressions:
- Length [tex]\( l = 2a + 11 \)[/tex]
- Width [tex]\( w = 5a - 12 \)[/tex]
- Height [tex]\( h = a + 6 \)[/tex]

2. Recall the formula for the volume of a rectangular prism:

[tex]\[ V = l \times w \times h \][/tex]

3. Substitute the given expressions for [tex]\( l \)[/tex], [tex]\( w \)[/tex], and [tex]\( h \)[/tex] into the volume formula:

[tex]\[ V = (2a + 11) \times (5a - 12) \times (a + 6) \][/tex]

4. Expand the expression step by step:

First, we need to find the product of the first two expressions, [tex]\((2a + 11)(5a - 12)\)[/tex].

[tex]\[ (2a + 11)(5a - 12) = 2a(5a - 12) + 11(5a - 12) \\ = 2a \cdot 5a + 2a \cdot (-12) + 11 \cdot 5a + 11 \cdot (-12) \\ = 10a^2 - 24a + 55a - 132 \\ = 10a^2 + 31a - 132 \][/tex]

5. Multiply the result by [tex]\( (a + 6) \)[/tex]:

[tex]\[ (10a^2 + 31a - 132)(a + 6) = 10a^2(a + 6) + 31a(a + 6) - 132(a + 6) \\ = 10a^2 \cdot a + 10a^2 \cdot 6 + 31a \cdot a + 31a \cdot 6 - 132 \cdot a - 132 \cdot 6 \\ = 10a^3 + 60a^2 + 31a^2 + 186a - 132a - 792 \\ = 10a^3 + (60a^2 + 31a^2) + (186a - 132a) - 792 \\ = 10a^3 + 91a^2 + 54a - 792 \][/tex]

6. Simplify the expression to get the final volume:

[tex]\[ V = 10a^3 + 91a^2 + 54a - 792 \][/tex]

So, the expression that represents the volume of the box is:

[tex]\[ 10a^3 + 91a^2 + 54a - 792 \][/tex]

From the given options, the correct choice is:

[tex]\[ \boxed{10a^3 + 91a^2 + 54a - 792} \][/tex]