Х^2-5x-84=0
D=25+336=19^2
x1=(5+19)/2=12
x2=(5-19)/2=-7
A)2sinπ/6cos(3π/2+x)=2*1/2*sinx=sinx
б)2cos(π+x)cosπ/3=2*1/2*(-cosx)=-cosx
в)(-2sinasinπ/4)/-√2sina=√2sina/√2sina=1
г)√3cosa/(2sinπ/3cosa)=√3:(2*√3/2)=√3/√3=1
д)(cosx-cos3x)/(sin²x+cos²x+cos²x-sin²x)=(-2sin(-x)sin2x)/2cos²x=
4sin²xcosx/2cos²x=2tgxsinx
e)(sin6x+sin2x)/(sin²2x+cos²2x+cos²2x-sin²2x)=2sin4xcos2x/2cos²2x=sin4x/cos2x=
2sin2xcos2x/cos2x=2sin2x
(1\2)^(-5)·4^(-2)+(1\9)·3²=2^5·2^(-4)+1\9·9=2^(5-4)+1=2+1=3
2
1 40/81
4
8
2
3 5/16
4
-1125