Х²-x=56. x²-x-56=0. D=(-1)²-4*(-56)=225. x=1+15/2. x=8
1
(cos²2t-sin²2t)(cos²2t+sin²2t)=cos²2t-sin²2t=cos4t
2
sina=-√(1-cos²a)=-√(1-225/289)=-√(64/289)=-8/17
sin2a=2sinacosa=2*(-8/17)*15/17=-240/289
cos2a=cos²a-sin²a=225/289-64/289=161/289
tg2a=sin2a/cos2a=-240/289:161/289=-240/289*289/161=-240/161
3
(sin3acos2b+cos3asin2b-sin3acos2b+cos3asin2b)/(cos3acos2b-sin3asin2b+
+cos3acos2b+sin3asin2b)=2cos3asin2b/2cos3acos2b=sin2b/cos2b=tg2b
4
sina=-√(1-cos²a)=-√(1-4/9)=-√5/3
cosb=-√(1-sin²b)=-√(1-1/9)=-2√2/3
sin2a=2sinacosa=2*(-√5/3)*2/3=-4√5/9
sin2b=2sinbcosb=2*1/3*(-2√2/3)=-4√2/9
cos2a=cos²a-sin²a=4/9-5/9=-1/9
cos2b=cos²b-sin²b=8/9-1/9=7/9
sin(2a+2b)=sin2acos2b+cos2asin2b=-4√5/9*7/9-1/9*(-4√2/9)=
=-28√5/81+4√2/81=4(√2-7√5)/81
X-y+by-bx=2bx-2by-y+x
by+2by-bx-2bx=0
3by-3bx=0
3b(y-x)=0
y-x=0
А) х= 2 (5/12) - 1 (2/9)
Х= 1 (7/36)
Б) 14/х=7/3 /*3х
42=7х
7х=42/:7
Х=6
3a-5(7-2a)=4
3a-35+10a=4
3a+10a=4+35
13a=39
a=39/13
a=3