4sin'2x-3sinxcosx-5cos'2x =8sinxcosx-3sinxcosx-10(1+cos^2 x) =5tanx (1/1+tan^2 x)-10(1+1/(1+tan^2 x)) =5*3 /(1+9) -10 (1+1/10) =1.5-11 =-9.5
