Метод сложения:
Система:
5х+2у=-1, домножаем обе части уравнения на 2
2х-3у=-8 домножаем обе части уравнения на 5
Система:
10х+4у=-2
10х-15у=-40 вычитаем из первого уравнения второе, получаем:
0+19у=38
у=2 подставляем в любое уравнение системы, получаем:
10х+8=-2
10х=-10
х=-1
ответ: (-1; 2)
Метод подстановки:
Система:
х=-0,4у-0,2
2(-0,4у-0,2)-3у=-8 Решаем второе уравнение системы:
-0,8у-0,4-3у=-8
-3,8у=-7,6
у=2
Подставляем в первое уравнение системы:
х=-0,8-0,2
х=-1
ответ: (-1;2)
Решение покажу на примере денег. Значит было в начале 100% или 100 рублей. Забрали из этих 100 30% то есть 100-30=70 рублей или 70 %. Потом отняли от 70 рублей 60%. Составим пропорцию: 70 руб=100%
х руб= 60%
После решения системы а это значит перемножить крест накрест (70*60=100х)
Отсюда х=42 рубля- это деньги или те 60% которые отняли.
70-42=28рублей или 28%. зная что 28% это 42 метра проводо составим пропорцию
28%=42
100%=х
Отсюда 28х=42*100 х=4200\28= 150 м. ответ 150 м
Объяснение:
WRITING Choose ONE of the topics and write. Topic 1: You are a charitable volunteer in your city and always give a hand to those who are in need: clean the apartments of the disabled people; bring food to animal refuges to feed homeless animals; organise campaigns to raise money and collect toys and clothes for the local orphanages. Your new idea is to write a formal letter to the local mayor to ask him/her for any help he/she can provide to help your charity organisation. Include in your letter the following information: • The title of your charity organisation: • What you have done/are doing aiready; • How you would like the mayor to help your charity organisation. Use appropriate style and examples in your letter.WRITING Choose ONE of the topics and write. Topic 1: You are a charitable volunteer in your city and always give a hand to those who are in need: clean the apartments of the disabled people; bring food to animal refuges to feed homeless animals; organise campaigns to raise money and collect toys and clothes for the local orphanages. Your new idea is to write a formal letter to the local mayor to ask him/her for any help he/she can provide to help your charity organisation. Include in your letter the following information: • The title of your charity organisation: • What you have done/are doing aiready; • How you would like the mayor to help your charity organisation. Use appropriate style and examples in your letter.WRITING Choose ONE of the topics and write. Topic 1: You are a charitable volunteer in your city and always give a hand to those who are in need: clean the apartments of the disabled people; bring food to animal refuges to feed homeless animals; organise campaigns to raise money and collect toys and clothes for the local orphanages. Your new idea is to write a formal letter to the local mayor to ask him/her for any help he/she can provide to help your charity organisation. Include in your letter the following information: • The title of your charity organisation: • What you have done/are doing aiready; • How you would like the mayor to help your charity organisation. Use appropriate style and examples in your letter.WRITING Choose ONE of the topics and write. Topic 1: You are a charitable volunteer in your city and always give a hand to those who are in need: clean the apartments of the disabled people; bring food to animal refuges to feed homeless animals; organise campaigns to raise money and collect toys and clothes for the local orphanages. Your new idea is to write a formal letter to the local mayor to ask him/her for any help he/she can provide to help your charity organisation. Include in your letter the following information: • The title of your charity organisation: • What you have done/are doing aiready; • How you would like the mayor to help your charity organisation. Use appropriate style and examples in your letter.WRITING Choose ONE of the topics and write. Topic 1: You are a charitable volunteer in your city and always give a hand to those who are in need: clean the apartments of the disabled people; bring food to animal refuges to feed homeless animals; organise campaigns to raise money and collect toys and clothes for the local orphanages. Your new idea is to write a formal letter to the local mayor to ask him/her for any help he/she can provide to help your charity organisation. Include in your letter the following information: • The title of your charity organisation: • What you have done/are doing aiready; • How you would like the mayor to help your charity organisation. Use appropriate style and examples in your letter.