If M₁ = {x : x is a perfect-square natural number less than 20}, what is M₁?
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Answer and explanation
Correct answer: M₁ = {1, 4, 9, 16}
The positive perfect squares are obtained by squaring natural numbers: 1² = 1, 2² = 4, 3² = 9, and 4² = 16. The next square, 5² = 25, is not less than 20 and must be excluded. Therefore the complete set of perfect-square natural numbers below 20 is M₁ = {1, 4, 9, 16}.
Frequently asked questions
What is the correct answer to this question?
M₁ = {1, 4, 9, 16}
Why is this the correct answer?
The positive perfect squares are obtained by squaring natural numbers: 1² = 1, 2² = 4, 3² = 9, and 4² = 16. The next square, 5² = 25, is not less than 20 and must be excluded. Therefore the complete set of perfect-square natural numbers below 20 is M₁ = {1, 4, 9, 16}.
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.
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