If A is the set of all integers whose square lies strictly between 10 and 20, what is A?
Answer and explanation
Correct answer: A = {−4, −3, 3, 4}
The phrase “strictly between 10 and 20” means 10 < x² < 20. The only perfect square in this range is 16, because 3² = 9 is too small and 5² = 25 is too large. Solving x² = 16 gives x = 4 or x = −4. Hence A = {−4, 4}, not the four-element set shown in option A. Therefore, the original options contain no correct answer; option A must be corrected to A = {−4, 4}.
Frequently asked questions
What is the correct answer to this question?
A = {−4, −3, 3, 4}
Why is this the correct answer?
The phrase “strictly between 10 and 20” means 10 < x² < 20. The only perfect square in this range is 16, because 3² = 9 is too small and 5² = 25 is too large. Solving x² = 16 gives x = 4 or x = −4. Hence A = {−4, 4}, not the four-element set shown in option A. Therefore, the original options contain no correct answer; option A must be corrected to A = {−4, 4}.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: The Empty Set, Finite and Infinite Sets, Equal Sets.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
