MediumMathematicsHigh School (11–12)Functions and Calculus › Relations and FunctionsNumericalBoard Exam

Let R = {(x, y) : y = 3x - 1} be a relation from A = {1, 2, 3, 4} to ℕ…

Try it on paper first. A hint, the key idea and the worked solution are here when you need them.

Let $R = \{(x, y) : y = 3x - 1\}$ be a relation from $A = \{1, 2, 3, 4\}$ to $\mathbb{N}$ . Write $R$ in roster form, and find its domain and range.

Need a reminder? The key ideaShow

$A \times B$ holds every pair $(a, b)$ , and $n(A \times B) = n(A)\,n(B)$ . A relation is any subset of $A \times B$ . On one set, a relation that is reflexive, symmetric and transitive is an equivalence relation.

The worked solution

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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

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