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Let \(\mathrm{A}=\{1,2,3,4,5\}\) and the functions \(\mathrm{f}: \mathrm{A} \rightarrow \mathrm{A}\) and \(\mathrm{g}: \mathrm{A} \rightarrow \mathrm{A}\) be defined by \(\mathrm{f}(1)=3, \mathrm{f}(2)=5, \mathrm{f}(3)=3, \mathrm{f}(4)=1, \mathrm{f}(5)=2 ; \mathrm{g}(1)=4\), \(\mathrm{g}(2)=1, \mathrm{~g}(3)=1, \mathrm{~g}(4)=2, \mathrm{~g}(5)=3\). Then
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The correct answer is:
\(\operatorname{fog}=\{(1,1),(2,3),(3,3),(4,5),(5,3)\}\)
We have
\(\begin{aligned}
& (\mathrm{gof})(1)=\mathrm{g}(\mathrm{f}(1))=\mathrm{g}(3)=1 \\
& (\mathrm{fog})(1)=\mathrm{f}(\mathrm{g}(1))=\mathrm{f}(4)=1 \\
& (\mathrm{gof})(2)=\mathrm{g}(\mathrm{f}(2))=\mathrm{g}(5)=3 \\
& (\mathrm{fog})(2)=\mathrm{f}(\mathrm{g}(2))=\mathrm{f}(1)=3 \\
& (\mathrm{gof})(3)=\mathrm{g}(\mathrm{f}(3))=\mathrm{g}(3)=1 \\
& (\mathrm{fog})(3)=\mathrm{f}(\mathrm{g}(3))=\mathrm{f}(1)=3 \\
& (\mathrm{gof})(4)=\mathrm{g}(\mathrm{f}(4))=\mathrm{g}(1)=4 \\
& (\mathrm{fog})(4)=\mathrm{f}(\mathrm{g}(4))=\mathrm{f}(2)=5 \\
& (\mathrm{gof})(5)=\mathrm{g}(\mathrm{f}(5))=\mathrm{g}(2)=1 \\
& (\mathrm{fog})(5)=\mathrm{f}(\mathrm{g}(5))=\mathrm{f}(3)=3 \\
& \therefore \mathrm{gof}=\{(1,1),(2,3),(3,1),(4,4),(5,1)\} \\
& \text { and fog }=\{(1,1),(2,3),(3,3),(4,5),(5,3)\} .
\end{aligned}\)
\(\begin{aligned}
& (\mathrm{gof})(1)=\mathrm{g}(\mathrm{f}(1))=\mathrm{g}(3)=1 \\
& (\mathrm{fog})(1)=\mathrm{f}(\mathrm{g}(1))=\mathrm{f}(4)=1 \\
& (\mathrm{gof})(2)=\mathrm{g}(\mathrm{f}(2))=\mathrm{g}(5)=3 \\
& (\mathrm{fog})(2)=\mathrm{f}(\mathrm{g}(2))=\mathrm{f}(1)=3 \\
& (\mathrm{gof})(3)=\mathrm{g}(\mathrm{f}(3))=\mathrm{g}(3)=1 \\
& (\mathrm{fog})(3)=\mathrm{f}(\mathrm{g}(3))=\mathrm{f}(1)=3 \\
& (\mathrm{gof})(4)=\mathrm{g}(\mathrm{f}(4))=\mathrm{g}(1)=4 \\
& (\mathrm{fog})(4)=\mathrm{f}(\mathrm{g}(4))=\mathrm{f}(2)=5 \\
& (\mathrm{gof})(5)=\mathrm{g}(\mathrm{f}(5))=\mathrm{g}(2)=1 \\
& (\mathrm{fog})(5)=\mathrm{f}(\mathrm{g}(5))=\mathrm{f}(3)=3 \\
& \therefore \mathrm{gof}=\{(1,1),(2,3),(3,1),(4,4),(5,1)\} \\
& \text { and fog }=\{(1,1),(2,3),(3,3),(4,5),(5,3)\} .
\end{aligned}\)
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