Пусть вся дорога 1 (единица), тогда х время, за которое первая бригада может отремонтировать дорогу, а у время второй бригады. Совместная работа двух бригад 6 ч. Если первая бригада отремонтирует 3/5 дороги, то время затратит (3/5)÷(1/х)=3х/5 ; если вторая бригада отремонтирует оставшуюся часть: 1-3/5=2/5 дороги. то время затратит (2/5)÷(1/у)=2у/5 , и времени они затратят 12 часов. Составим два уравнения:
1/х+1/у=1/6
3х/5+2у/5=12
Выделим х во втором уравнении:
3х/5+2у/5=12
15х+10у=300
3х+2у=60
х=(60-2у)/3
Подставим значение х в первое уравнение:
3/(60-3у)+1/у=1/6
18у+360-12у=60у-2у²
2у²-54у+360=0
у²-27у+180=0
D=9
у₁=12 часов вторая бригада может отремонтировать дорогу самостоятельно.
х₁=(60-2*12)/3=36/3=12 часов первая бригада может отремонтировать дорогу самостоятельно.
у₂=15 часов вторая бригада может отремонтировать дорогу самостоятельно.
х₂=(60-2*15)/3=30/3=10 часов первая бригада может отремонтировать дорогу самостоятельно.
ответ: Или первая за 12 часов и вторая за 12 часов; Или первая за 10 часов и вторая за 15 часов.
0 және не знаю как гOTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
Write the correct preposition, then complete the
sentences for you.
Write the correct preposition, then complete the
sentences for you.
Write the correct preposition, then complete the
sentences for you.
OTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
OTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
OTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
OTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
OTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
OTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
OTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
OTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
OTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
OTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
OTBET:
the afternoon, learn work
in lunchtime, I eat pizza and drink juice
in night, I watch TV or play mobile games
in weekend, I go to picnicin
Write the correct preposition, then complete the
sentences for you.
Write the correct preposition, then complete the
sentences for you.
Write the correct preposition, then complete the
sentences for you.
Write the correct preposition, then complete the
sentences for you.
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Смежные углы равны, зн. угол AOC=BOD=72°
ответ : АОВ и СОD = 108°
AOC и BOD=72°