Решениеееееееееееееееееее
5 умножить на х ровно трем.
х=3/5
х= 3/5 три пятых или 0,6.
Думаю так,напиши если,что нет так - переделаю.
(3а-2b)³+8b³=((3a-2b)+2b)·((3a-2b)²-(3a-2b)·2b+4b²)=(3a-2b+2b)·(9a²-12ab+4b²-(3a-2b)·2b+4b²)=3a·(9a²-12ab+8b²+(-3a+2b)·2b)=3a·(9a²-12ab+8b²-6ab+4b²)=3a·(9a²-18ab+12b²)=3a·3(3a²-6ab+4b²)=9a·(3a²-6ab+4b²).
4t²+2t+1 / 8t³+1 = 4t²+2t+1 / (2+t) (4t² + 2t + 1) = 1/ (2+t)
Sin2α=2sinα*cosα⇒sinα*cosα =(sin2α)/2. sin(π -α) =sinα
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9.
cosπ/9*cos2π/9*cosπ/3*cos4π/9 =(1/2)*cosπ/9*cos2π/9*cos4π/9=
(1/2)*sinπ/9*cosπ/9*cos2π/9*cos4π/9 / sinπ/9=
(1/4)*sin2π/9*cos2π/9*cos4π/9 / sinπ/9=(1/8)*sin4π/9*cos4π/9 / sinπ/9=
(1/16)*sin8π/9 / sinπ/9=(1/16)*sin(π-π/9) / sinπ/9=(1/16)*sinπ/9) / sinπ/9 =1/16.
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10. y =sinx/8 -sin(x/8 -π/2) =sinx/8 -sin(-(π/2 - x/8))=sinx/8 +cosx/8 =√2sin(x/8 +π/4).
T =16π.
* * * sin(x+T)/8 +π/4) =sin(x/8+π/4 +T/8) = sin(x/8+π/4).
T/8 =2π⇒T =16π.