Question

1) Resolva pelo método da substituição


a) { x+y=14
{ x-y=8

b) { 2x-y=23
{ x+3y=22

Answer 1

a) 2x= 22
x=22/2
x= 11
11+y=14
y=14-11
y=3
b) {2x-y=23
{x+3y= 22 (.2)
{2x-y=23
{2x-6y=44 (-1)
{2x-y=23
{-2x+6y=-44
5y=-21
y=-21/5
y= -4,2
x+3.(-4,2)=22
x-12,6=22
x=22+12,6
x= 34,6

Answer 2

Bom Dia!

A)

$\left\{\begin{matrix}x+y=14\\x-y=8\\\end{matrix}\right.$

_____________________________

$\boxed{x+y=14}$

$\mathbf{x=14-y}$

_____________________________

$\boxed{x-y=8}$

$\mathit{14-y-y}=\textup{8}$

$\textup{14-2y}=\textup{8}$

$\textup{-2y}=\textup{8-14}$

$\textup{-2y}=\textup{-6}$

$\textup{y}=\frac{-6}{-2}$

$\textbf{\boxed{\boxed{y=3}}}$

_____________________________

$\boxed{x=14-y}$

$\textup{x}=\textup{14-3}$

$\textbf{\boxed{\boxed{x=11}}}$

________________________________________________________

B)

$\left\{\begin{matrix}2x-y=23\\x+3y=22\\\end{matrix}\right.$

_____________________________

$\boxed{2x-y=23}$

$\textup{-y}=\textup{23-2x}$ *-1

$\textup{y}=\textup{-23+2x}$

_____________________________

$\boxed{x+3y=22}$

$\textup{x+3}\times\textup{-23+2x}=\textup{22}$

$\textup{x-69+6x}=\textup{22}$

$\textup{7x-69}=\textup{22}$

$\textup{7x}=\textup{22+69}$

$\textup{x}=\frac{91}{7}$

$\textbf{\boxed{\boxed{13}}}$

_____________________________

$\boxed{x=14-y}$

$\textup{x}=\textup{14-3}$

$\textbf{\boxed{\boxed{x=11}}}$

_____________________________

$\boxed{y=-23+2x}$

$\textup{y}=\textup{-23+2}\times\textup{13}$

$\textup{y}=\textup{-23+26}$

$\textbf{\boxed{\boxed{y=3}}}$

________________________________________________________

Att;Guilherme Lima