Ну, как-то так..................................................
3x+5y=16 * 2
<span>2x+3y=9 * 3
6x+10y=32
6x+9y=27
y=5
2x+15=9
x=-3
Ответ -3 5</span>
7X^2 - X - 8 = 0
D = 1 - 4*7*(-8) = 1 + 224 = 225
V D = 15
X1 = ( 1 + 15 ) : 14 = 16/14 = 8/7 = 1 1/7
X2 = ( - 14) : 14 = ( - 1 )