первое нет, второе нет. третье да, четвертое да, пятое нет
![9 \sin( \alpha ) \times \cos(3 \alpha ) + 9 \sin( \alpha ) \times \cos( \alpha ) - 3 \sin(3 \alpha ) \times \cos(3 \alpha ) - 3 \sin(3 \alpha ) \times \cos( \alpha ) \\ \\ 9 \sin( \alpha ) \times \cos(3 \alpha ) + \frac{9 \sin(2 \alpha ) }{2} - \frac{3 \sin(6 \alpha ) }{2} - 3 \sin(3 \alpha ) \times \cos( \alpha ) \\ \\ 9 \sin( \alpha ) \times \cos(3 \alpha ) + \frac{9 \sin(2 \alpha ) - 3 \sin(6 \alpha ) }{2} - 3 \sin(3 \alpha ) \times \cos( \alpha )](https://tex.z-dn.net/?f=9+%5Csin%28+%5Calpha+%29++%5Ctimes++%5Ccos%283+%5Calpha+%29++%2B+9+%5Csin%28+%5Calpha+%29++%5Ctimes++%5Ccos%28+%5Calpha+%29++-+3+%5Csin%283+%5Calpha+%29++%5Ctimes++%5Ccos%283+%5Calpha+%29++-+3+%5Csin%283+%5Calpha+%29++%5Ctimes++%5Ccos%28+%5Calpha+%29++%5C%5C++%5C%5C+9+%5Csin%28+%5Calpha+%29++%5Ctimes++%5Ccos%283+%5Calpha+%29++%2B++%5Cfrac%7B9+%5Csin%282+%5Calpha+%29+%7D%7B2%7D++-++%5Cfrac%7B3+%5Csin%286+%5Calpha+%29+%7D%7B2%7D++-+3+%5Csin%283+%5Calpha+%29++%5Ctimes++%5Ccos%28+%5Calpha+%29++%5C%5C++%5C%5C+9+%5Csin%28+%5Calpha+%29++%5Ctimes++%5Ccos%283+%5Calpha+%29++%2B++%5Cfrac%7B9+%5Csin%282+%5Calpha++%29+-+3+%5Csin%286+%5Calpha+%29++%7D%7B2%7D++-+3+%5Csin%283+%5Calpha+%29++%5Ctimes++%5Ccos%28+%5Calpha+%29+)
~•~•~•ZLOY_TIGROVSKIY~•~•~•
Привет,
1) 78х²+305х-348=0
D=b²-4ac=305²-4*305*(-348)=93025+108576=201601=449²
х1,2=(-305±449)/156
х1=12/13. х2=-29/6
2)551х²-1604х+1085=0
D=1604²-4*551*1085=181476=426²
х1,2=(-1604±426)/1102
х1=35/19. х2=31/29
3)1312х²-2615х+1302=0
D=2615²-4*1312*1302=5329=73²
х1,2=(-2615±73)/2624
х1=42/41. х2=31/32