3 1 6
__________=________________ - ___________
(х-3)² х+3 (х-3)(х+3)
3(х+3)=(х-3)² -6(х-3)
3х+9-х²+6х-9+6х-18=0
-х²+9х-18=0
х²-9х+18=0
Д=81-72=9
х1=(9+3+/2=6
х2=(9-3)/2=3 ОДЗ х≠3 х≠-3
ответ х=6
A₁=20 d=-4 a₃₂=?
a₃₂=a₁+(32-1)*d=20+31*(-4)=20-124=-104.
Ответ: a₃₂=-104.
Cos5a*cos4a-sin2a*cos2a= <span>cos5a*cos4a - sin2a*cos2a * 2 * 1/2 = </span><span>cos5a*cos4a-1/2 * sin4a</span>= <span>cos5a*cos4a-sin5a*sin4a = cos(5a+4a) = cos9a</span>