1/2^2*a^2+2*1/2^2x-3=0
1/4x^2+a-3=0
D=b^2-4ac
D=1+12/4=1+3=4
1)A1=-b-кореньD/2a=-1-корень4/1/2=-3/1/2=-6
2)A2+-b+кореньD/2a=-1+2/1/2=1/1/2=2
Ответ:при А=-6 и 2
По моему так
cos(x-y)=cosx*cosy+sinx*siny cos(x+y)=cosx*cosy-sinx*sinysin(x-y)=sinx*cosy-cosx*siny sin(x+y)=sinx*cosy+cosx*siny<span>.
Ответ: </span>sinx*cosy+cosx*siny
Ctg(2π-5π/13)=-ctg5π/13
cos(3π-π/3)=cos(π-π/3)=-cosπ/3=-1/2
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