• 072920 77839
  • info@smartachievers.in
Menu
Back
  • JEE ADVANCE
  • JEE MAIN
  • NEET
  • BITSAT
  • CBSE BOARD
  • UP BOARD
  • CUET
JEE ADVANCE
  • CLASS XI - XII
  • CRASH COURSE
CRASH COURSE
JEE MAIN
  • CLASS XI - XII
  • CRASH COURSE
CRASH COURSE
NEET
  • CLASS XI - XII
  • CRASH COURSE
BITSAT
  • CLASS XI - XII
CBSE BOARD
  • CLASS IX
  • CLASS X
  • CLASS XI
  • CLASS XII
  • CLASS VI
  • CLASS VII
  • CLASS VIII
UP BOARD
  • CLASS IX
  • CLASS X
  • CLASS XI
  • CLASS XII
CUET
  • CRASH COURSE
Courses


Solution


Q.

The number of solutions of the equation 4sin2x-4cos3x+9-4cosx=0; x∈[-2π,2π] is :                      [2024]
1 0  
2 3  
3 1  
4 2  

Ans.

(1)

We have, 4sin2x-4cos3x+9-4cosx=0

⇒4(1-cos2x)-4cos3x+9-4cosx=0

⇒4cos3x+4cos2x+4cosx=13

Ist clear that L.H.S. ≤12 and never 13

∴  Solution does not exists.