X² - 3x - 5 = 0
D = 9 + 20 = 29
x1 = (3-√29)/2
x2 = (3+√29)/2
1) 1/x1 + 1/x2 = 2/(3-√29) + 2/(3+√29) = (6+2√29+6-2√29)/(9-29) = 12/(-20) = -3/5 = -0,6
2) x1² + x2² = (3-√29)² + (3+√29)² = 9 -6√29 + 29 + 9 + 6√29 + 29 = 76
3) x1/x2 + x2/x1 = (x1² + x2²)/(x1*x2) = 76/((3-√29)(3+√29)) = 76/(9-29) = 76/(-20) = -19/5 = -3,8
1 слагаемое 100 , 2 слагаемое 99 .Соответственно 100 + 99 = 199 . Получается 3217 - 199 = 3018
<span>17 х- х +5 х-19=170
21х=170+19
21х=189
х=189:21
х=9
</span>
<span>7*(10+2)
7</span>·10+7·2=70+14=84.
7+7+7+7+7+7+7+7+7+7+7+7=84.
123, 321, 211, 222, 231, 132