4х ^2 - 4х + 1 = 0; (2x-1)^2=0; x=1/2
х^2- 16х - 17 = 0 ; (x-17)(x+1)=0;x1=17; x2=-1
0,3х^2 + 5х -2=0; 3x^2+50x-20=0 D=2500+240=2740;
![x_{1} = \frac{-50+ \sqrt{2740} }{6}](https://tex.z-dn.net/?f=+x_%7B1%7D+%3D+%5Cfrac%7B-50%2B+%5Csqrt%7B2740%7D+%7D%7B6%7D+)
;
![x_{2} = \frac{-50-\sqrt{2740} }{6}](https://tex.z-dn.net/?f=+x_%7B2%7D+%3D+%5Cfrac%7B-50-%5Csqrt%7B2740%7D+%7D%7B6%7D+)
<span>х^2 - 4х + 5 = 0</span>; корней нет
Y'=(y+2)ctgx
y'/(y+2)=ctgx
∫(y'/(y+2)dx=∫ctgxdx
∫dy/(y+2)=ln(sinx)+c
ln(y+2)=ln(sinx*e^c)
y+2=e^c*sinx
y=e^c*sinx-2