(5b-8)+(4-b)=5b-8+4-b=4b-4
(7a+14)-(2-5a)=7a+14-2+5a=12a+12
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1)sin^2x+2sinx*cosx-3cos^2x=0 |÷cos^2x
tg^2x+2tgx-3=0
tgx=t
t^2+2t-3=0
x1=-3(не верно) ,x2=1
tgx=1
x=πn,n€Z
2)cos5x=-1/2
5x=+-2π/3+2πn. ,|÷5
x=+-2π/15+2πn/5, n€Z
K=f`(x0)
f`=-15cos5x-1/2sin2x
f`(π/6)=-15cos5π/6-1/2sinπ/3=-15-(-√3/2)-1/2√3/2=15√3/2-√3/4=30√3/4-√3/4=29√3/2