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What is the perimeter of a square with a side length of 6 cm?
- A. 24 cm
- B. 12 cm
- C. 18 cm
- D. 36 cm
Correct Answer: A
Rationale: The perimeter of a square is calculated by multiplying the side length by 4 since all sides are equal. In this case, the side length is 6 cm, so the perimeter is 4 * 6 = 24 cm. Therefore, choice A, 24 cm, is the correct answer. Choices B, C, and D are incorrect because they do not reflect the correct calculation for the perimeter of a square.
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Simplify (x^2 - y^2) / (x - y)
- A. x + y
- B. x - y
- C. 1
- D. (x + y)/(x - y)
Correct Answer: A
Rationale: The expression x^2 - y^2 is a difference of squares, which follows the identity: x^2 - y^2 = (x + y)(x - y). Therefore, the given expression becomes: (x^2 - y^2) / (x - y) = (x + y)(x - y) / (x - y). Since (x - y) appears in both the numerator and the denominator, they cancel each other out, leaving x + y. Thus, the simplified form of (x^2 - y^2) / (x - y) is x + y. Therefore, the correct answer is A (x + y). Option B (x - y) is incorrect as it does not result from simplifying the given expression. Option C (1) is incorrect as it does not account for the variables x and y present in the expression. Option D ((x + y)/(x - y)) is incorrect as it presents the simplified form in a different format than the correct answer.
Half of a circular garden with a radius of 11.5 feet needs weeding. Find the area in square feet that needs weeding. Round to the nearest hundredth. Use 3.14 for π.
- A. 2.4
- B. 207.64
- C. 15.1
- D. 30.1
Correct Answer: B
Rationale: The formula for the area of a full circle is calculated as Area = π (radius²). When finding the area of half a circle, we multiply by 0.5. Thus, the formula becomes Area = 0.5 π (radius²). Given that the radius of the circular garden is 11.5 feet, the calculation using π = 3.14 is as follows: Area = 0.5 3.14 (11.5²) = 0.5 3.14 132.25 = 0.5 415.27 = 207.64 square feet. Therefore, the correct answer is B. Choices A, C, and D are incorrect because they do not reflect the correct calculation for finding the area of half a circular garden with a radius of 11.5 feet.
Apply the polynomial identity to rewrite (a + b)².
- A. a² + b²
- B. 2ab
- C. a² + 2ab + b²
- D. a² - 2ab + b²
Correct Answer: C
Rationale: When you see something like (a + b)², it means you're multiplying (a + b) by itself:
(a + b)² = (a + b) (a + b)
To expand this, we use the distributive property (which says you multiply each term in the first bracket by each term in the second bracket):
Multiply the first term in the first bracket (a) by both terms in the second bracket:
a a = a²
a b = ab
Multiply the second term in the first bracket (b) by both terms in the second bracket:
b a = ab
b b = b²
Now, add up all the results from the multiplication:
a² + ab + ab + b²
Since ab + ab is the same as 2ab, we can simplify it to:
a² + 2ab + b²
So, (a + b)² = a² + 2ab + b².
This is known as a basic polynomial identity, and it shows that when you square a binomial (a two-term expression like a + b), you get three terms: the square of the first term (a²), twice the product of the two terms (2ab), and the square of the second term (b²).
Therefore, the correct answer is C (a² + 2ab + b²)
What is the result of multiplying 3/5 by 5/7?
- A. 3/7
- B. 1
- C. 2
- D. 4
Correct Answer: A
Rationale: To multiply fractions, multiply the numerators together and the denominators together. Multiplying 3/5 by 5/7 gives (3*5)/(5*7) = 15/35. This fraction simplifies to 3/7 by dividing the numerator and denominator by their greatest common factor, which is 5. Therefore, the correct answer is 3/7. Choices B, C, and D are incorrect as they do not result from multiplying 3/5 by 5/7.
Simplify the expression: 2x + 3x - 5.
- A. 5x - 5
- B. 5x
- C. x - 5
- D. 2x - 5
Correct Answer: A
Rationale: To simplify the expression 2x + 3x - 5, follow these steps: Identify and combine like terms. The terms 2x and 3x are both 'like terms' because they both contain the variable x. Add the coefficients of the like terms: 2x + 3x = 5x. Simplify the expression. After combining the like terms, the expression becomes 5x - 5, which includes the simplified term 5x and the constant -5. Thus, the fully simplified expression is 5x - 5, making Option A the correct answer. This method ensures all terms are correctly simplified by combining similar elements and retaining constants.