Remember that, for the definition of a function composition:
[tex](f\circ g)(x)=f(g(x))[/tex]Then:
[tex](f\circ g)(1)=f(g(1))[/tex]Evaluate g taking x=1 :
[tex]\begin{gathered} g(x)=2x-12 \\ \Rightarrow g(1)=2(1)-12 \\ =2-12 \\ =-10 \end{gathered}[/tex]Since g(1)=-10, then:
[tex]f(g(1))=f(-10)[/tex]Evaluate f at x=-10:
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