![(x^2+4)(x^2+4x-17)+60=0](https://tex.z-dn.net/?f=%28x%5E2%2B4%29%28x%5E2%2B4x-17%29%2B60%3D0)
<span>Раскрываем скобки
</span>
![x^4+4x^3-17x^2+4x^2+16x-68+60=0 \\ x^4+4x^3-13x^2+16x-8=0 \\ x^4-x^3+5x^3-5x^2-8x^2+8x+8x-8=0 \\ x^3(x-1)+5x^2(x-1)-8x(x-1)+8(x-1)=0 \\ (x-1)(x^3+5x^2-8x+8)=0 \\ x-1=0 \\ x_1=1 \\ x^3+5x^2-8x+8=0](https://tex.z-dn.net/?f=x%5E4%2B4x%5E3-17x%5E2%2B4x%5E2%2B16x-68%2B60%3D0+%5C%5C+x%5E4%2B4x%5E3-13x%5E2%2B16x-8%3D0+%5C%5C+x%5E4-x%5E3%2B5x%5E3-5x%5E2-8x%5E2%2B8x%2B8x-8%3D0+%5C%5C+x%5E3%28x-1%29%2B5x%5E2%28x-1%29-8x%28x-1%29%2B8%28x-1%29%3D0+%5C%5C+%28x-1%29%28x%5E3%2B5x%5E2-8x%2B8%29%3D0+%5C%5C+x-1%3D0+%5C%5C+x_1%3D1+%5C%5C+x%5E3%2B5x%5E2-8x%2B8%3D0)
<span>Используя формулой Карнадо.
</span>
![x_2= \frac{-5+ \sqrt[3]{-413+42 \sqrt{30} } + \sqrt[3]{-413-42 \sqrt{30} } }{3}](https://tex.z-dn.net/?f=x_2%3D+%5Cfrac%7B-5%2B+%5Csqrt%5B3%5D%7B-413%2B42+%5Csqrt%7B30%7D+%7D+%2B+%5Csqrt%5B3%5D%7B-413-42+%5Csqrt%7B30%7D+%7D+%7D%7B3%7D+)
Ответ:
![x_1=1; \\ x_2= \frac{-5+ \sqrt[3]{-413+42 \sqrt{30} } + \sqrt[3]{-413-42 \sqrt{30} } }{3}](https://tex.z-dn.net/?f=x_1%3D1%3B+%5C%5C+x_2%3D+%5Cfrac%7B-5%2B+%5Csqrt%5B3%5D%7B-413%2B42+%5Csqrt%7B30%7D+%7D+%2B+%5Csqrt%5B3%5D%7B-413-42+%5Csqrt%7B30%7D+%7D+%7D%7B3%7D)
Сosa=15/17,sina=√(1-225/289)=√64/289=8/17,tga=8/17:15/17=8/15
cosb=1/4;sinb=√(1-1/16)=√15/16=√15/4,tgb=√15
tg(a+b)=(tga+tgb)/(1-tgatgb)=(8+15√15)/(15-120√15)
tg(a-b)=(tga-tgb)/(1+tgatgb)=(8-15√15)/(15+120√15)
tg2a=2tga/(1-tg²a)=16/15:(1-64/225)=240/181
tg2b=2tgb/(1-tg²b)=-√15/7
8√х+5√у-√х-11√у=(<span>8√х-√х)+(5</span>√у<span>-11√у)=7</span>√х-6√у
7c/(c+2) -(c-8)/3(c+2) * 84/c(c-8)=7c/(c+2) - 28/c(c+2)=(7c²-28)/c(c+2)=
=7(c-2)(c+2)/c(c+2)=7(c-2)/c=(7c-14)/c