de ex:^2 inseamna la puterea 2
daca n=0
E=2[(-1)^0-3(-1)^0]+(-1)²=2(1-3)+1=2·(-2)+1=-4+1=-3
daca n=1
E=2[(-1)^1-3·(-1)²]+(-1)³=2(-1-3)-1=-8-1=-9
daca n=2
E=2[(-1)²-3(-1)^4]+(-1)^4=2(1-3)+1=-4+1=-3
daca n=3
E=2[(-1)³-3(-1)^6]+(-1)^5=2(-1-3)-1=-8-1=-9
deci daca n este nr.impar adica n=1,3,5,7,9....... atunci E=-9
daca n este nr.par adica n=0,2,4,6,8.... atunci E=-3
