1.3(1,2+1,8)-2*1,2*1,8=4,68
2.3*1,2+1,8-2*1,2*1,8=1,08
3.3(1,2-1,8)+2*1,2*1,8=2,52
4.3*1,2-1,8+2*1,2*1,8=-2,52
1)2((5+1)^2+1)=74
2)4(3-(5+1)^2)=-132
3)((5+1)5-8)2=-36
4)5*5-(5-1)/3=7
<span>cos17cos73=0.5(cos90+cos56)</span>
<span><span>sin13cos21=0.5(sin34-sin8)</span></span>
<span><span><span>cos4cos86=0.5(cos90+cos82)</span></span></span>
<span><span><span>cos90=0</span></span></span>
<span><span><span>cos56=cos(90-34)=sin34</span></span></span>
<span><span><span>cos82=cos(90-8)=sin8</span></span></span>
<span><span><span><span>cos17cos73-sin13cos21-cos4cos86=0.5(sin34-sin34+sin8-sin8)=0</span></span></span></span>
270/x-270/(x+30)=1.5
(270/x-270/(x+30))*x=1.5x
8100/(x+30)=1.5x
8100/(x+30)*(x+30)=1.5x*(x+30)
8100=1.5x²+45x
-1.5x²-45x+8100=0
D=-45²-4*(-1.5)*8100=50625
x1=(√50625-(-45))/(2*(-1.5))=-90
x2=(-√50625-(-45))/(2*(-1.5))=60 км в час автобус
60+30=90 км в час автомобиль
10x2-17x+34=7x2-26x+28
10x2-17x+34-7x2+26x-28=0
3x2+9x+6=0 | :3
x2+3x+2=0
За Т.Виета
x1 x x2 =2
x1 + x2 = -3
x1 = -2
x2 = -1
1. Делим на cos^2x
3sin^2x/ cos^2x - 4 sinx/cosx +1 = 0
3tg^2X - 4 tgx +1=0
пусть tgx = t
3t^2-4t+1=D= 16-12=4
t1=4+2/6 = 1
t2 = 4-2/6=1/3
1)tgx=1 2)tgx = 1/3
x = П/4+Пn, nєZ x= arctgx1/3+Пn, nєZ
2. sin²x - 9sinx*cosx+3 cos²x=-sin^2x - cos^2x
sin²x - 9sinx*cosx+3 cos²x+sin^2x + cos^2x=0
2sin²x- 9sinx*cosx+4 cos²x=0 /cos^2x
2th^2x - 9tgx +4=0
tgx=t
2t^2-9t+4=0
D=31-32 =49
t1=4
t2=1/2
1) 2)
tgx=4 tgx=1/2
x=arctg4 +Пn, nєZ x=arctg1/2+Пn, nєZ