Ответ: -5/6
Пошаговое объяснение:
7/18 *(-1 4/7) - (-4/21)*( -1 1/6)
1)7/18 *(-1 4/7)= 7/18 *(-11/7) = -11/18
2)(-4/21)*( -1 1/6)= (-4/21)*( -7/6)=2/9
3)-11/18 - 2/9= -11/18 - 4/18 = -15/18 =-5/6
(x - 12 23/40) + 5 8/15 = 13 19/24
x = 12 23/40 + 13 19/24 - 5 8/15
x = 20 + (23/40 + 19/24 - 8/15)
x = 20 + (69 + 95 - 64)/120
x = 20 5/6
3x²-x-4x+2=0
3x²-5x+2=0
D=25-24=1
√D=1
x1=(5-1)/6=4/6=2/3
x2=(5+1)/6=6/6=1