TÌM X∈[0;14] COS3 X−4COS2 X +3COS X−4=0 ( KH Ố I D_2002 ) ÐS

22. - DE THI LUONG GIAC TRONG CAC DE THI DHCD TU 2002 DEN 2012 CODAP
DE THI LUONG GIAC TRONG CAC DE THI DHCD TU 2002 DEN 2012 CODAP

22. Tìm x∈[0;14] cos3 x−4cos2 x +3cos x−4=0 ( Kh ố i D_2002 )

ðS: 3 5 7

; ; ;

x π x π x π x π

= = = =

2 2 2 2

 

x x