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3x^3 - 16x^2 + 8 = 0
3x^3 + 2x^2 - 18x^2 - 12x + 12x + 8 = 0
(3x + 2)(x^2 - 6x + 4) = 0
x1 = -2/3
D/4 = 3^2 - 4 = 9 - 4 = 5
x2 = 3 - √5
x3 = 3 + √5
3) 24-(3у+1)(4у-5)=(11-6у)(2у-1)+6
24-(12у²-15у+4у-5)=22у-11-12у²+6у+6
24-12у²+15у-4у+5=22у-11-12у²+6у+6
-12у²+15у-4у-22у+12у²-6у=-11+6-24-5
-17у=-34
у=2
4) (6у+2)(5-у)=47-(2у-3)(3у-1)
30у-6у²+10-2у=47-(6у²-2у-9у+3)
30у-6у²+10-2у=47-6у²+2у+9у-3
30у-6у²-2у+6у²-2у-9у=47-3-10
17у=34
у=2
D=в^2-4ас
100-4*0.2*125
100-100=0
корней нет
=c0s^2 a+((cos(60+a)+cos(60-a))^2-2cos(60+a) *cos(60-a)=cos^2 a+
+(cos60 *cosa-sin60*sina +cos60 *cosa-sin60*sina)^2 -2cos(60+a)*cos(60-a)=
=cos^2 a+(2cos60 cosa)^2 -2*(cos(60+a+60-a) +cos(60+a-60+a)) /2=
=cos^2 a +cos^2 a -cos120-cos2a=2cos^2 a+(-cos60)-cos2a=
=2cos^2 a-(-1/2)-(cos^2 a -sin^2 a)=2cos^2 a +1/2-cos^2 a+sin^2 a=
=cos^2 a+sin^2 a +1/2=1+1/2=1,5
Что не так , пиши, посмотрю!