При c>0 (положительных) к примеру: при c=1 -5*1-1^2=-7; при c=20 -5*20-20^2=-500
7+5(-9х+7)=-3
7-45х+35=-3
10+35=45х
х=1
Сosx≥0⇒x∈[-π/2+2πn;π/2+2πn,n∈Z]
cosx=0⇒x=π/2+πn,n∈z
tg²x-3=0
tg²x=3
tgx=-√3⇒x=-π/3+2πn,n∈Z
tgx=√3⇒x=π/3+2πn,n∈Z
Y'(x)=(Sin5x)'Cos6x+Sin5x*(Cos6x)-{Cos5x)'Sin6x-Cos5x(Sin6x)'=5Cos5x*Cos6x-6Sin5x*Sin6x+5Sin5x*Sin6x-6Cos5x*Cos6x=-(Sin5x*Sin6x+Cos5x*Cos6x)
2x+y=12(:2)
x+y=6 наверно так