(12 3 5 4 1(chi) 9 la pile)) nhtin cae chuydn tri dude thuc hign tii phaisang trai nhu hap thanh cua the Anh xa).Vay sgna = (-1) s = -1Co the lam each khan: Cam nghich the cua a la (1, 5), (2, 5),(3, 5), (4, 5), (3, 4).Vay a có 5 nghich the nen sgna = -1.b) Ta hay tinh sS nghich the cua boa)) vi (1,[r]