<span>2sin (4pi/3-x) -sin (4pi/3+x)= 0
-2sin(</span>π/3-x)+sin(π/3+x)=0
-2sinπ/3cosx+2cosπ/3sinx+sinπ/3cosx+cosπ/3sinx=
=-sinπ/3cosx+3cosπ/3sinx=-√3/2*cosx+3*1/2*sinx=-√3/2cosx+3/2*sinx
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-√3/2cosx+3/2*sinx=0/cosx
3/2*tgx-√3/2=0
3/2*tgx=√3/2
tgx=-√3/3
x=-π/6+πk,k∈z
128-19-36-29-12= 32 книги (учебники)
32/128=0,25 - вероятность
Xy+(x-y)=1
xy(x-y)=-6
xy=a x-y=b
a+b=1⇒a=1-b
a*b=-6
b(1-b)=-6
b²-b-6=0
b1*b2=1 U b1*b2=-6
b1=-2⇒a1=3
x-y=-2 U xy=3
x=y-2
y²-2y-3=0
y1+y2=2 U y1*y2=-3
y1=3⇒x1=1
y2=-1⇒x2=-3
b2=3⇒a2=-2
x-y=3 U xy=-2
x=y+3
y²+3y+2=0
y3+y4=-3 U y3+y4=2
y3=-2⇒x3=1
y4=-1⇒x4=2
(1;3) (-3;-1) (1;-2) (2;-1)