<span>sin(105)=sin(45+60)=sin45*cos60+cos45*sin60=√2/2*(1/2+√3/2)=√2(1+√3)/4</span>
4x=-6y
7y-2x=20
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2x+3y=0
-2x+7y=20/+
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10y=20, y=2
2x=-3.2=-6, x=-3
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/x,y/=/-3,2/
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3х - у = 3
3х - 2у = 0
Решение способом сложения
- 3х + у = - 3
- 3х + 3х + у - 2у = - 3 + 0
- у = - 3
у = 3
3х - 3 = 3
3х = 6
Х = 2
Ответ ( 2 ; 3 )
6(4х-3)-5(10х-3)=24х-18-50х+15=-26х-3
