f(-2) = - [tex]\frac{1}{2}[/tex] × (-2) + 1 = 1 + 1 = 2
f(1) = - [tex]\frac{1}{2}[/tex] × 1 + 1 = - [tex]\frac{1}{2}[/tex] + 1 = [tex]\frac{1}{2}[/tex]