3x+6-5=-2
3x-1=-2
3x=-1
x=-1/3
<span>1,1/5+5/9+4/5+4/9= 1 1/5+4/5 +5/9+4/9=1 5/5 + 9/9= 2+1=3</span>
1)cos2x-sinx=0
cos²x-sin²x-sinx=0
1-2sin²x-sinx=0
2sin²x+sinx-1=0
D=1+8=9
sinx1=(-1+3)/4 ;sinx2=(-1-3)/4
sinx1=1/2; sinx2=-1
x1=(-1)^(n+1)π/6+πn, n∈Z
x2=-π/2+2πn, n∈Z
2)sin2x-cosx