... ba nghiệm phân biệt 1 k 1 3 0 k 4 − < − < ⇔ < <Câu II ( 3,0 điểm ) a. ( 1đ ) 3x 4 3x 4 2x 2 2(2x 2)2 2x 183 9 3 3 3x 4 4x 4 x7(3x 4) (4x 4) − −− −≥= ⇔ = ⇔ − = − ⇔ ... a2 AN. BD'1 3 3cos arccos3a9 93 3 AN . BD'.a 322a [AN, BD'] (1 ;4; 3),AB (a;0;0) a(1;0;0)2Do đó : = = =uuur uuuur uuuruuur uuuur3a [AN, BD'].ABa2d (AN, BD')226 [AN, BD']a ... a. (1đ ) pt⇔x 2logsin 2x 4 −+>0⇔ x 20 1x 4 −< <+ ( vì 0 < sin2 < 1 ) x 2 x 2 x 20 0 0x 4 x 4 x 4 x 2 x 2 61 1 0 0x 4 x 4 x 4 − − −< < <...