Let $A=\{1,2,3,4\} .$ Let $f: A \rightarrow A$ and $g: A \rightarrow A$,
defined by $f=\{(1,4),(2,1),(3,3),(4,2)\}$ and $g=\{(1,3),(2,1),(3,2),(4,4)\}$
Find (i) g of (ii) f o g (iii) f o f.
(i) $\mathrm{g}$ o $\mathrm{f}$
To find: $g$ o $f$
Formula used: $g$ o $f=g(f(x))$
Given: $f=\{(1,4),(2,1),(3,3),(4,2)\}$ and $g=\{(1,3),(2,1)$
$(3,2),(4,4)\}$
Solution: We have,
$g \circ f(1)=g(f(1))=g(4)=4$
$g \circ f(2)=g(f(2))=g(1)=3$
$g \circ f(3)=g(f(3))=g(3)=2$
$g \circ f(4)=g(f(4))=g(2)=1$
Ans) g of $f=\{(1,4),(2,3),(3,2),(4,1)\}$
(ii) $f \circ g$
To find: f o g
Formula used: f o g = f(g(x))
Given: f = {(1, 4), (2, 1), (3, 3), (4, 2)} and g = {(1, 3), (2, 1),
(3, 2), (4, 4)}
Solution: We have,
fog(1) = f(g(1)) = f(3) = 3
fog(2) = f(g(2)) = f(1) = 4
fog(3) = f(g(3)) = f(2) = 1
fog(4) = f(g(4)) = f(4) = 2
Ans) f o g = {(1, 3), (2, 4), (3, 1), (4, 2)}
(iii) f o f
To find: $f$ o $f$
Formula used: $f$ o $f=f(f(x))$
Given: $f=\{(1,4),(2,1),(3,3),(4,2)\}$
Solution: We have,
fof $(1)=f(f(1))=f(4)=2$
fof $(2)=f(f(2))=f(1)=4$
fof $(3)=f(f(3))=f(3)=3$
fof $(4)=f(f(4))=f(2)=1$
Ans) fo f $=\{(1,2),(2,4),(3,3),(4,1)\}$