bantu nomer 8 ya....

ga tau ya, ini bener atau salah...

f(p+2) = f(p) + f(p-1) + 2p

f(5) = 3
f(3+2) = 3
f(3) + f(3-1) + 2(3) = 3
f(3) + f(2) + 6 = 3
f(3) + f(2) = -3 

f(0) = f(3 + (-3))
      = f(3) + f(3-1) + (-3)(3)
      = f(3) + f(2) - 9
      = -3 - 9
      = -12

f(1) = f(3 + (-2))
      = f(3) + f(3-1) + (-2)(3)
      = f(3) + f(2) - 6
      = -3 - 6
      = -9

f(2) = f(3 + (-1))
      = f(3) + f(3-1) + (-1)(3)
      = f(3) + f(2) - 3
      = -3 - 3
      = -6

Jadi
f(0) + f(1) + f(2) 
= -12 - 9 - 6
= -27