Question:
Let $R=\left\{\left(x, x^{2}\right): x\right.$ is a prime number less than 10$\} .$
(i) Write $\mathbf{R}$ in roster form.
(ii) Find dom (R) and range (R).
Solution:
i) $\left\{\left(x, x^{2}\right): x\right.$ is a prime number less than 10$\}$.
Roster form: $R=\{(1,1),(2,4),(3,9),(5,25),(7,49)\}$
ii) The domain of $R$ is the set of first co-ordinates of $R$
Dom(R) = {1, 2, 3, 5, 7}
The range of $R$ is the set of second co-ordinates of $R$
Range $(R)=\{1,4,9,25,49\}$