А) х2=2+6=8
х5=5+6=11
х10=10+6=16
б) х2=(2*2-1)/3=1
х5=( 2*5-1)/3=3
х10=(2*10-1)/3=6,3
в) х2=2²=4
х5=5²=25
х10=10²=100
г)х2=2(2-1)=2
х5=5(5-1)=20
х10=10(10-1)=90
д) х2=2³-2=8-2=6
х5=5³-5=120
х10=10³-10=990
е) х2=(-1)²*2=2
х5=(-1)5 *5=-5
х10=(-1)10*10=10
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Cos 4x = корень из (1-0,3^2)=корень из 0,91
<span>cos 8x=cos 2*4x=2*cos4x*sin4x=2*корень из 0,91*0,3=0,6*корень из 0,91</span>
An=-12;-6;...
a1=-12
d=an+1-an= -6-12=-18
a17= a1+d(17-1)
a17= -12-18*18= -12-324=-336
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</span><span>
1)cos40</span>°соs20°= 1/2(cos(40°+20°)+cos(40°-20°) = 1/2(cos 60° + cos20°)= =1/2(1/2 +cos20°) = 1/4 + 1/2cos20°
<span>
2) cos(</span>π/4+y)sin(π/4-y)= 1/2(sin (π/4+у+π/4-у)+sin(π/4+у-π74+у)) =
= 1/2(sin π/2+sin 2у)= 1/2(1+sin 2у) = 1/2 + 1/2sin2y
<span>
3)cos(x+y)cos(x-y) = </span>1/2(cos(х+у+х-у)+cos(х+у-х+у) = 1/2(cos2х + cos2у)=
=1/2cos2x + 1/2cos2y