9х2+6х-3=0 (сократим на 3)
3х2+2х-1=0
D=2*2-4*3(-1)=4+12=16; Корень из D=4
х"=(-2-4):2*3=-6:6=-1
х=(-2+4):2*3=2:6=1/3
Ответ: первый х=-1; второй х=1/3
141-6=135km/h
135*1000/3600=37.5m/s
37.5*12=450m
<span>52:(13 1/12-5 1/12)*(6 17/20+3/5+13 2/15-13 1/4) = 47 2/3,
1) </span>13 1/12-5 1/12 = 8,
2) 52 : 8 = 52/8 = 6 1/2,
3) 6 17/20+3/5+13 2/15-13 1/4 = (6 + 13 - 13) + (17/20 + 3/5 + 2/15 - 1/4) = 6 + (51/60 + 36/60 + 8/60 - 15/60) = 6 + 80/60 = 6 + 1 1/3 = 7 1/3,
4) 6 1/2 * 7 1/3 = 13/2 * 22/3 = 143/3 = 47 2/3