1)567/(12*0,09)=56700/12*9=6300/12=2100/4=525р
2)530/(25*0,04)=530/1=530р
3)572,4/(9*0,12)=57240/9*12=6360/12=1060/2=530р
1 случай
A-b²
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2sin^2 x -4sinx cosx +sin^2 x+cos^2 x=0; (sin2x=2sinx cosx; 1=sin^2 x+cos^2 x)
3sin^2 x -4sinx cosx+cos^2 x=0 /cos^2 x=/0!
3tg^2 x-4tgx+1=0
y=tgx; 3y^2-4y+1=0; D1=4-3=1; y1=(2-1)/3=1/3; y2=(2+1)/3=1
tgx=1/3 ili tgx=1
x=arctg(1/3)+pi n x=pi/4 +pin; n-целое
Ответ. arctg(1/3)+pi n; pi/4+pi n; n-celoe