Answer:
-6+-6+-4 +0
Step-by-step explanation:
Let n=0
(0-3) (0+2) = -3*2 = -6
Let n = 1
(1-3) (1+2) = -2*3 = -6
Let n=2
(2-3) (2+2) =-1*4 = -4
Let n=3
(3-3) (3+2)=0*5 =0
Sum them all up
