Дана арифметическая прогрессия 2; 12; 22.найдите сумму первых пяти её членов

Если прогрессия 2,12,22,32,42. То сумма членов равна 110

Объяснение:

All my friends are toxic, all ambitionless

So rude and always negative

I need new friends, but it's not that quick and easy

Oh, I'm drowning, let me breathe

I'm better off all by myself

Though I'm feeling kinda empty without somebody else

Oh, I hear you crying out for help

But you never showed for me when I was ringing your cell phone

Oh, you don't know how it feels to be alone

Baby, oh, I'll make you know, I'll make you know, oh

(Oh, I'm drowning, let me breathe)

(I'm drowning, let me breathe)

(Oh, I'm drowning, let me breathe)

(I'm drowning, let me breathe)

But life is immaculate, backing it up a bit

Countin' my hours and knocking on wood

Avoiding my opposites, chewing on chocolate

Had a bit limited time, but I should

Be good for a minute, don't want to admit it

I'm running on seconds, I'm rigid, I'm screwed

Don't know what to do, I'm thinking of you

I'm drinking up bottles and bottles of booze

I'm better off all by myself

Though I'm feeling kinda empty without somebody else

Oh, I hear you crying out for help

But you never showed for me when I was ringing your cell phone

Oh, you don't know how it feels to be alone

Baby, oh, I'll make you know, I'll make you know, oh

I fell into your river

That's where you told me lies

You said that I'd feel better

But this is where good guys die

You took my pride away

But you cannot take my light

I'll find another way out

But now you're taking my life

Don't you see how I—

I'm better off all by myself

Though I'm feeling kinda empty without somebody else

Oh, I hear you crying out for help

But you never showed for me when I was ringing your cell phone

Oh, you don't know how it feels to be alone

Baby, oh, I'll make you know, I'll make you know, oh

I'm better off all by myself

Though I'm feeling kinda empty without somebody else

Oh, I hear you crying out for help

But you never showed for me when I was ringing your cell phone

Oh, you don't know how it feels to be alone

Baby, oh, I'll make you know, I'll make you know, oh

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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.