1)x^2 - 5x -8 = 0
D=(-5)^2 - 4*1*(-8) = 25 +32 = 57 (2 корня) D>0
2)3x^2 - x - 2 = 0
D =1 + 24 = 25 (2 корня) D>0
3) 9^2 - 4 *1*(-3) = 81+12=93 (2 корня) D>0
4) 36-44=-8 D<0 нет корней
5)36-14=22 (2 корня) D>0
6)4 - 50 = -46 D<0 нет корней
7) 196-196=0 D=0 (1 корень) x = -b/2a
8)2.56-2.56=0 D=0 (1 корень) x = -b/2a
![(2 \frac{5}{6} +1 \frac{5}{13} ): \frac{1}{39} =( \frac{17}{6} + \frac{18}{13} )*39 = ( \frac{221}{78} + \frac{108}{13 } )*39 = \frac{329}{78}*39 = \\ = \frac{329}{13*6}*13*3= \frac{329}{2} =164 \frac{1}{2}](https://tex.z-dn.net/?f=%282+%5Cfrac%7B5%7D%7B6%7D+%2B1+%5Cfrac%7B5%7D%7B13%7D+%29%3A+%5Cfrac%7B1%7D%7B39%7D+%3D%28+%5Cfrac%7B17%7D%7B6%7D+%2B+%5Cfrac%7B18%7D%7B13%7D+%29%2A39+%3D+%28+%5Cfrac%7B221%7D%7B78%7D+%2B+%5Cfrac%7B108%7D%7B13+%7D+%29%2A39+%3D++%5Cfrac%7B329%7D%7B78%7D%2A39+%3D+%5C%5C+%3D++%5Cfrac%7B329%7D%7B13%2A6%7D%2A13%2A3%3D+%5Cfrac%7B329%7D%7B2%7D+%3D164+%5Cfrac%7B1%7D%7B2%7D+)
Можно по другому: раскрыть скобки
![(2 \frac{5}{6} +1 \frac{5}{13} ): \frac{1}{39} =( \frac{17}{6} + \frac{18}{13} )*39 =\frac{17}{6} *39+ \frac{18}{13} *39 = \frac{17}{2} *13+ 18 *3 = \\ \frac{221}{2} + 54= 110 \frac{1}{2} +54=164 \frac{1}{2}](https://tex.z-dn.net/?f=%282+%5Cfrac%7B5%7D%7B6%7D+%2B1+%5Cfrac%7B5%7D%7B13%7D+%29%3A+%5Cfrac%7B1%7D%7B39%7D+%3D%28+%5Cfrac%7B17%7D%7B6%7D+%2B+%5Cfrac%7B18%7D%7B13%7D+%29%2A39+%3D%5Cfrac%7B17%7D%7B6%7D+%2A39%2B+%5Cfrac%7B18%7D%7B13%7D+%2A39+%3D+%5Cfrac%7B17%7D%7B2%7D+%2A13%2B+18+%2A3+%3D+%5C%5C++%5Cfrac%7B221%7D%7B2%7D+%2B+54%3D+110+%5Cfrac%7B1%7D%7B2%7D+%2B54%3D164+%5Cfrac%7B1%7D%7B2%7D+)
2х²-10х=0
2х(х-5)=0
2х₁=0
х₁=0
х₂-5=0
х₂=5
0;5