Just substitute the values of x's to the given equation.
1.) x^2 - 4
[tex] {(5)}^{2} - 4 = 21[/tex]
[tex] {(3)}^{2} - 4 = 5[/tex]
[tex] {(0)}^{2} - 4 = - 4[/tex]
[tex] {( - 3)}^{2} - 4 = 5[/tex]
[tex] {( - 5)}^{2} - 4 = 21[/tex]
2.) 18 - 3x
[tex]18 - 3( - 4) = 18 + 12 = 30[/tex]
[tex]18 - 3( - 3) =18 + 9 = 27[/tex]
[tex]18 - 3( - 1) = 18 + 3 = 21[/tex]
[tex]18 - 3(0) = 18 - 0 = 18[/tex]
[tex]18 - 3(7) = 18 - 21 = - 3[/tex]
