If K₁ = {x : x ∈ N, x² − 5x + 6 ≤ 0}, what is the roster form of K₁?
Answer and explanation
Correct answer: K₁ = {2, 3}
Factor the quadratic: x² − 5x + 6 = (x − 2)(x − 3). Since the parabola opens upward, the expression is less than or equal to zero between the roots, including the endpoints. Thus 2 ≤ x ≤ 3. The natural numbers in this interval are only 2 and 3, so the roster form is K₁ = {2, 3}.
Frequently asked questions
What is the correct answer to this question?
K₁ = {2, 3}
Why is this the correct answer?
Factor the quadratic: x² − 5x + 6 = (x − 2)(x − 3). Since the parabola opens upward, the expression is less than or equal to zero between the roots, including the endpoints. Thus 2 ≤ x ≤ 3. The natural numbers in this interval are only 2 and 3, so the roster form is K₁ = {2, 3}.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Sets and their representations.