(а+3)(а-4)=а²-4а+3а-12=а²-а-12
(а-1)(6-а)= 6а-а²-6+а=-а²+7а-6
А15=а1+14d=-0,7+14*(-3,6)=-51,1
10sin'2x -2sinxcosx= 8cos'2x => 10sin'2x-2sinxcosx-8cos'2x=0 => 5sinx'2 - sinxcosx - 4cos'2x=0 => (5sinx+4cosx)*(sinx-cosx)=0 1) sinx= -4cosx 2) sinx=cosx Sinx/cosx=-4 => tgx =-4/5 => x = arctg(-4/5)
- х^3 + х(Х+2) = - х^3 +х( х^2 +4х +4)= - х^3 + х^3 +4х^2 +4х= 4х^2+4х =
= 4* (1/4)^2 + 4* 1/4 = 4 * 1/16 + 4*1/4= 1/4+1= 1 1/4 =1,25