which equation is not a function

ATI TEAS 7

TEAS Math Practice Test

1. Which of the following equations does not represent a function?

A. y = x^2
B. y = sqrt(x)
C. x = y^2
D. y = 2x + 1

Correct answer: C

Rationale: An equation represents a function if each input (x-value) corresponds to exactly one output (y-value). In the equation x = y^2, for a single x-value, there are two possible y-values (positive and negative square root), violating the definition of a function. This violates the vertical line test, where a vertical line intersects the graph in more than one point for non-functions. Choices A, B, and D all pass the vertical line test and represent functions, making them incorrect answers.

2. If a tree grows an average of 4.2 inches in a day, what is the rate of change in its height per month? Assume a month is 30 days.

A. 0.14 inches per month
B. 4.2 inches per month
C. 34.2 inches per month
D. 126 inches per month

Correct answer: D

Rationale: The tree grows at an average rate of 4.2 inches per day. To find the rate of change per month, multiply the daily growth rate by the number of days in a month (30 days): 4.2 inches/day × 30 days = 126 inches per month. Therefore, the rate of change in the tree's height is 126 inches per month, making option D the correct answer. Option A is incorrect because it miscalculates the rate based on daily growth. Option B is incorrect as it doesn't account for the total days in a month. Option C is incorrect as it overestimates the monthly growth rate.

3. How do you find the least common multiple?

A. List all multiples of the numbers, then find the smallest common one
B. List all factors of the numbers, then find the largest common one
C. Divide the largest number by the smallest
D. Multiply the two numbers together

Correct answer: A

Rationale: The correct way to find the least common multiple is to list all the multiples of each number and then identify the smallest common multiple. Choice A is correct because it describes the correct process. Listing factors, as suggested in choice B, helps in finding the greatest common factor, not the least common multiple. Dividing the largest number by the smallest, as mentioned in choice C, does not help find the least common multiple. Multiplying the two numbers together, as stated in choice D, results in their least common multiple when the numbers have no common factors.

4. Kimberley earns $10 an hour babysitting, and after 10 p.m., she earns $12 an hour, with the amount paid being rounded to the nearest hour accordingly. On her last job, she worked from 5:30 p.m. to 11 p.m. In total, how much did Kimberley earn on her last job?

A. $45
B. $57
C. $62
D. $42

Correct answer: C

Rationale: Kimberley worked from 5:30 p.m. to 11 p.m., which is a total of 5.5 hours before 10 p.m. (from 5:30 p.m. to 10 p.m.) and 1 hour after 10 p.m. The earnings she made before 10 p.m. at $10 an hour was 5.5 hours * $10 = $55. Her earnings after 10 p.m. for the rounded hour were 1 hour * $12 = $12. Therefore, her total earnings for the last job were $55 + $12 = $67. Since the amount is rounded to the nearest hour, the closest rounded amount is $62. Therefore, Kimberley earned $62 on her last job. Choice A is incorrect as it does not consider the additional earnings after 10 p.m. Choices B and D are incorrect as they do not factor in the hourly rates and the total hours worked accurately.

5. 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.