Evaluate the expression -3 x 5.

Correct Answer: A

Rationale: The correct answer is A, which is -15. When you multiply -3 by 5, you get -15. The negative sign in front of the 3 indicates a negative value, and when multiplied by a positive number like 5, the result remains negative. Choices B, C, and D are incorrect because they do not reflect the correct multiplication of -3 and 5.

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.

Correct Answer: A

Rationale: The absolute value of x is equal to 10 when x is either -10 or 10. Therefore, the correct answer is A. Choices B, C, and D are incorrect because they do not satisfy the equation |x| = 10. For choice B, -11 and 11 do not satisfy the condition. Choices C and D also do not provide solutions that meet the equation's requirement.

Correct Answer: C

Rationale: The difference between two numbers is found by subtracting one from the other. When two numbers are equal, subtracting them results in 0, because any number minus itself is always 0. Therefore, the difference between two equal numbers is always zero, making option C the correct answer. Option A ('Negative') and option B ('Positive') are incorrect as they do not represent the result of subtracting two equal numbers, which always yields zero. Option D ('Not enough information') is also incorrect as the difference between two equal numbers is definitively known to be zero.

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.

Correct Answer: D

Rationale: To find the fourth vertex of a parallelogram, we can use the properties of a parallelogram. Opposite sides of a parallelogram are parallel and equal in length. Therefore, we can determine the fourth vertex by extending the line formed by the first two points. If we extend the line from (1, 2) to (3, 4), we find that it has a slope of 1. This means that extending the line from (3, 4) by the same slope will give us the fourth vertex. By adding 2 units to both x and y coordinates of (5, 6), we get (7, 8) as the coordinates of the fourth vertex. Therefore, the correct answer is (7, 8). Choices A, B, and C are incorrect as they do not satisfy the properties of a parallelogram and the given coordinate points.

Correct Answer: C

Rationale: To solve for x, add 5 to both sides of the equation: 3x - 5 + 5 = 16 + 5, which simplifies to 3x = 21. Next, divide both sides by 3: x = 21 · 3 = 7. Therefore, the correct answer is x = 7, making option A the correct choice. Option C, '8,' is incorrect as it is not the solution obtained from the correct calculations. Options B and D, '5' and '9,' are also incorrect and not the solution to the given equation.

Correct Answer: D

Rationale: The formula for the area of a circle is: Area = π x (radius²). Given: Diameter = 16 cm, so Radius = Diameter / 2 = 16 / 2 = 8 cm. Now, calculate the area using π = 3.14: Area = 3.14 x (8²) = 3.14 x 64 = 200.96 cm². The correct answer is D (200.96 cm²) as it correctly calculates the area of the circle. Choices A, B, and C are incorrect as they do not represent the accurate area of the circle based on the given diameter and π value.

Correct Answer: B

Rationale: The correct answer is B: 30. To find the sum, you need to add 4 + 5 + 12 + 9, which equals 30, not 40 as stated in the original rationale. Choice A (20) is incorrect because it does not account for the correct addition of the numbers provided. Choice C (40) is incorrect as it represents the sum of the numbers incorrectly. Choice D (50) is also incorrect as it is not the sum of the given numbers.