Explicação passo-a-passo:
f(x)= - 2x +3
f(3)= -2.3+3
f(3)= -6+3
f(3)= -3
f(-1)= -2 .(-1) +3
f(-1)= 2 +3
f(-1) = 5
f(2/3) = -2.(2/3) +3
f(2/3)=-4/3 +3
f(2/3) = - 4 + 9
______
3
f(2/3)= 5/3
f(-3/2)= - 2.(-3/2) +3
f(-3/2)= +6/2+3
f(-3/2)= 3+3
f(-3/2)= 6
