Let X={2,3,4,5} and Y={7,9,11,13,15,17}. Define a relation f from X to Y by:
f={(x,y):xϵX, yϵY and y=2x+3}
(i) Write f in roster form.
(ii) Find dom(f) and range (f).
(iii) Show that f is a function from X to Y.
Let X={2,3,4,5} and Y=2x+3.
Now, x=2⇒y=(2×2+3)=7,
x=3⇒y=(2×3+3)=9,
x=4⇒y=(2×4+3)=11,
x=5⇒y=(2×5+3)=13,
(i) ∴f={(2,7),(3,9),(4,11),(5,13)}
(ii) Clearly, dom (f)={2,3,4,5} and range (f) ={7,9,11,13}⊆Y
(iii) It is clear that no two distinct ordered pairs in f have the same first coordinate.
∴ f is a function from X to Y.