... 5,−2, 3, 4) , a3=(3, 4, −1, 5, 7),a 4 =(3,−7, 4, 1,−7), a5=(0, 11,−5, 4, 4) . (DS. r =3hˆe.pttt) 4) a1=(2, 1, 4, 4, 17), a2=(0, 0, 5,−7, 9), a3=(2, 1,−6, 10,−11),a 4 =(8, 4, 1, 5, ... khˆong gian R 4 l`a dltt hay pttt1) a1=(1, 2, 3, 4) , a2=(1, 2, 3, 4) . (DS. Pttt)2) a1=(1, 2, 3, 4) , a2=(1,−2,−3, 4) . (DS. Pttt)3) a1=(1, 2, 3, 4) , a2=(3, 6, 9, 12). (DS. Pttt) 4) a1=(1, ... v`a−→BC.Tac´o−→AB(0,−2, 4, 4) ,−→AC (4, 4, 0, 2),−→BC (4, 6, 4, −2).´Ap du.ng di.nh ngh˜ıa dˆo.d`ai vecto.trong co.so.’tru..cchuˆa’n ta c´o−→AB =02+(−2)2 +4 2 +4 2=√36 =...