For point 4. Since -4 is less than zero, that is
[tex]-4<0[/tex]
then to find f(-4) replace x = -4 into x², like this
[tex]\begin{gathered} f(-4)=(-4)^2 \\ f(-4)=16 \end{gathered}[/tex]
For point 5. Since 3 is in the interval
[tex]0\le x\le3[/tex]
then
[tex]f(3)=2[/tex]
Finally, for point 6. Since 12 is greater than 3, that is
[tex]12>3[/tex]
then to find f(12) replace x = 12 into 4-x, like this
[tex]\begin{gathered} f(12)=4-12 \\ f(12)=-8 \end{gathered}[/tex]
