Question 2 (Essay Worth 10 points)

Part A: The area of a square is [tex]\left(4a^2 - 20a + 25\right)[/tex] square units. Determine the length of each side of the square by factoring the area expression completely. Show your work. (5 points)

Part B: The area of a rectangle is [tex]\left(9a^2 - 16b^2\right)[/tex] square units. Determine the dimensions of the rectangle by factoring the area expression completely. Show your work. (5 points)



Answer :

Certainly! Let's work through each part step by step.

### Part A: Factoring the Area Expression of the Square

The given area of the square is [tex]\(4a^2 - 20a + 25\)[/tex] square units. To determine the length of each side, we need to factor the quadratic expression completely.

1. Identify the expression to factor: [tex]\(4a^2 - 20a + 25\)[/tex].

2. Check if it is a perfect square trinomial: A perfect square trinomial takes the form [tex]\((ma + b)^2 = m^2a^2 + 2mab + b^2\)[/tex].

Let's rewrite [tex]\(4a^2 - 20a + 25\)[/tex]:
- The first term [tex]\(4a^2\)[/tex] can be written as [tex]\((2a)^2\)[/tex].
- The last term [tex]\(25\)[/tex] can be written as [tex]\(5^2\)[/tex].

3. Check the middle term: The middle term should be [tex]\(2 \times 2a \times 5\)[/tex] which is [tex]\(20a\)[/tex]. Since we have [tex]\(-20a\)[/tex] in the expression, it verifies:

[tex]\[ (2a - 5)^2 = 4a^2 - 20a + 25 \][/tex]

4. Factor the expression:

[tex]\[ 4a^2 - 20a + 25 = (2a - 5)^2 \][/tex]

5. Determine the length of each side of the square:
Since [tex]\((2a - 5)^2\)[/tex] represents the area of the square, the length of each side is:

[tex]\[ \boxed{2a - 5} \][/tex]

### Part B: Factoring the Area Expression of the Rectangle

The given area of the rectangle is [tex]\(9a^2 - 16b^2\)[/tex] square units. To determine the dimensions of the rectangle, we need to factor the expression completely.

1. Identify the expression to factor: [tex]\(9a^2 - 16b^2\)[/tex].

2. Recognize the form of the expression: This is a difference of squares which takes the form [tex]\(m^2 - n^2 = (m - n)(m + n)\)[/tex].

Let's rewrite [tex]\(9a^2 - 16b^2\)[/tex]:
- The first term [tex]\(9a^2\)[/tex] can be written as [tex]\((3a)^2\)[/tex].
- The second term [tex]\(16b^2\)[/tex] can be written as [tex]\((4b)^2\)[/tex].

3. Apply the difference of squares formula:

[tex]\[ 9a^2 - 16b^2 = (3a)^2 - (4b)^2 \][/tex]
[tex]\[ = (3a - 4b)(3a + 4b) \][/tex]

4. Determine the dimensions of the rectangle:
The dimensions of the rectangle are given by the factors:

[tex]\[ \boxed{(3a - 4b)} \quad \text{and} \quad \boxed{(3a + 4b)} \][/tex]

So, the factored dimensions of the rectangle are [tex]\(3a - 4b\)[/tex] and [tex]\(3a + 4b\)[/tex].