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Ответ:
Объяснение:
y(4a)= 5(4a)³+3(4a)=5×64a³+12a= 320a³+12a
2х<span>²-8х+1=0
D=b</span>²-4ac=(-8)<span>²-4*2*1=64-8=56
D=56
х1= -b-</span>√D/2а=8-√56/4= 8-2√14/4=2(4-√14)/4=4-<span>√14/2
х2=</span>-b+√D/2а=8+√56/4=8+2√14/4=2(4+√14)/4=4+<span>√14/2
Ответ:</span>4-√14/2 ; 4+√14/2
![2sin^22x-9cos^22x=2(1-cos^22x)-9cos^22= \\ =2-2cos^22x-9cos^22x=2-11cos^22x \\ 2-11*(-0,9)^2=2-11*0,81=2-8,81=-6,81](https://tex.z-dn.net/?f=2sin%5E22x-9cos%5E22x%3D2%281-cos%5E22x%29-9cos%5E22%3D+%5C%5C+%3D2-2cos%5E22x-9cos%5E22x%3D2-11cos%5E22x+%5C%5C+2-11%2A%28-0%2C9%29%5E2%3D2-11%2A0%2C81%3D2-8%2C81%3D-6%2C81)
2) угол в 3 четверти косинус будет отрицательный
![1+tg^2 \beta =\frac{1}{cos^2 \beta } \\ cos \beta =-\sqrt\frac{1}{1+tg^2 \beta}} \\ cos \beta =-\sqrt\frac{1}{1+(\frac{7}{24})^2}}=-\sqrt\frac{1}{1+\frac{49}{576}}}=-\sqrt\frac{1}{\frac{625}{576}}}=-\sqrt\frac{576}{625}}}=-\frac{24}{25}}}](https://tex.z-dn.net/?f=1%2Btg%5E2+%5Cbeta+%3D%5Cfrac%7B1%7D%7Bcos%5E2+%5Cbeta+%7D+%5C%5C+cos+%5Cbeta+%3D-%5Csqrt%5Cfrac%7B1%7D%7B1%2Btg%5E2+%5Cbeta%7D%7D+%5C%5C+cos+%5Cbeta+%3D-%5Csqrt%5Cfrac%7B1%7D%7B1%2B%28%5Cfrac%7B7%7D%7B24%7D%29%5E2%7D%7D%3D-%5Csqrt%5Cfrac%7B1%7D%7B1%2B%5Cfrac%7B49%7D%7B576%7D%7D%7D%3D-%5Csqrt%5Cfrac%7B1%7D%7B%5Cfrac%7B625%7D%7B576%7D%7D%7D%3D-%5Csqrt%5Cfrac%7B576%7D%7B625%7D%7D%7D%3D-%5Cfrac%7B24%7D%7B25%7D%7D%7D)
Х=4-у
3х-2у=17
х=4-у
3(4-у)-2у=17
х=4-у
12-3у-2у=17
х=4-у
у=17-12
х=4-у
у=5
х=4-5
у=5
х=-1
у=5