Переносит 8в левую часть
x^2-2x-8=0. Решаем квадратное уравнение
D(дескриминант)=4+32=36
Корень из D=6
x1=(2-6)/2=-2
x2=(2+6)/2=4
Решение задания смотри на фотографии
А)...=-3/2-3•½=-3/2-3/2=-3-3/2=-6/2=-3
Б)...=7,5:0,75-2=10-2=8
Направляющий вектор
![s_1= \left[\begin{array}{ccc}i&j&k\\2&1&0\\1&0&-3\end{array}\right] =i(-3)-j(-6)+k(-1)\\\\s=\lambda \cdot s=(3,-6,1)](https://tex.z-dn.net/?f=s_1%3D++%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Di%26j%26k%5C%5C2%261%260%5C%5C1%260%26-3%5Cend%7Barray%7D%5Cright%5D+%3Di%28-3%29-j%28-6%29%2Bk%28-1%29%5C%5C%5C%5Cs%3D%5Clambda+%5Ccdot+s%3D%283%2C-6%2C1%29)
Точки, принадлежащие прямой: z=0 --->
![\left \{ {{2x+y=-1} \atop {x=-10}} \right. \; \left \{ {{y=19} \atop {x=-10}} \right. \\\\A(-10,19,0)\\\\l:\; \; \frac{x+10}{3}=\frac{y-19}{-6}=\frac{z}{1}](https://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B%7B2x%2By%3D-1%7D+%5Catop+%7Bx%3D-10%7D%7D+%5Cright.+%5C%3B++%5Cleft+%5C%7B+%7B%7By%3D19%7D+%5Catop+%7Bx%3D-10%7D%7D+%5Cright.+%5C%5C%5C%5CA%28-10%2C19%2C0%29%5C%5C%5C%5Cl%3A%5C%3B+%5C%3B+%5Cfrac%7Bx%2B10%7D%7B3%7D%3D%5Cfrac%7By-19%7D%7B-6%7D%3D%5Cfrac%7Bz%7D%7B1%7D)