A.3
B.1
C.0
D.2

A.m=-3/4
B.m=-5/4
C.m=5/4
D.m=3/4

A.S=73/2
B.S=32/5
C.S=23/2
D.S=649/100~13/2

A.w=3-i
B.w=13-6i
C.w=1+i
D.w=4+3i

A.(P):2x+5y+4z-4=0
 
B.(P):2x+5y+4z+4=0
C.(P):2x+2y+z+2=0
D.(P):x+2y+z+3=0

A.K(4;0;-9)
B.K(-2;-2;-7)
C.K(-5;-1;-15)
D.K(7;3;-19)

A.b<0,cd<0
B.b>,cd<0
C.b0
D.b>0, cd>0

A.S=1210 hoặc S=220
B.S=-1210 hoặc S=-220
C.S=1210 hoặc S=-220
D.S=-1210 hoặc S=-220

A.x=1
B.x=3
C.x=2
D.x=4

A.(x+1)(x-1)(x+2)(x-3)
B.(x+1)(x-1)(x-2)(x+3)
C.(x+1)(x-1)(x-2)(x-3)
D.(x+1)(x-1)(x+2)(x+3)