resoudre-dans-pi-pi-cosx-cos2x-cos3x-0- Tinku Tara October 20, 2023 None 0 Comments FacebookTweetPin Question Number 198483 by Guillaume last updated on 20/Oct/23 resoudredans]−π;π]cosx+cos2x+cos3x=0 Answered by Frix last updated on 21/Oct/23 c=cosxc+2c2−1+4c3−3c=0c3+c22−c2−14=0(c+22)(c+12)(c−22)=0x=±3π4∨x=±2π3∨x=±π4 Answered by mr W last updated on 21/Oct/23 cosx+2cos2x−1+4cos3x−3cosx=04cos3x+2cos2x−2cosx−1=0letu=cosx4u3+2u2−2u−1=0(2u+1)(2u2−1)=0⇒u=−12⇒x=±120°⇒u=22⇒x=±45°⇒u=−22⇒x=±135° Answered by cortano12 last updated on 21/Oct/23 cos2x+(cos3x+cosx)=0cos2x+2cos2xcosx=0cos2x(1+2cosx)=0{cos2x=0⇒x=±π4cosx=−12⇒x=±2π3cos2x=cos3π2⇒x=±3π4 Terms of Service Privacy Policy Contact: info@tinkutara.com FacebookTweetPin Post navigation Previous Previous post: Solve-the-EDP-x-y-z-U-x-y-z-x-U-y-z-x-y-Next Next post: x-2-1-0-resoudre-dans-C- Leave a Reply Cancel replyYour email address will not be published. Required fields are marked *Comment * Name * Save my name, email, and website in this browser for the next time I comment.