Question

Решите систему уравнений
{x+y=3x+2y/4+3
{3(x-y)-6=x+5y/7
ДАЮ 45 БАЛЛОВ!

Answer 1

Решение:

_| х + у = 3х + 2у/4 + 3

| 3(х - у) - 6 = х + 5у/7

_| х - 3х - 2у/4 + у = 3

| 3х - 3у - х - 5у/7 = 6

_| -2х - 0.5у + у = 3

| 2х - 3у - 5у/7 = 6

_| -2х + 0.5у = 3

| 2х - 3у - 5у/7 = 6

-2х + 2х + 0.5у - 3у - 5у/7 = 3 + 6

-2.5у - 5у/7 = 9

$\frac{17.5y}{7} - \frac{5y}{7} = 9$

$\frac{12.5y}{7} = 9$

12.5у = 9 • 7

12.5у = 63

$y = \frac{63}{12.5}$

у = 5.04