Question

resolva os sistemas abaixo:
a)
{2x+y=6
{x+y=5

b)
{x+2y=1
{2x-y=11

c)
{x+3y=5
{x-y = -3

Answer 1

Método de substituição

a) 2x+y=6

x+y=5

2x+y=6

y=6-2x

x+6-2x=5

x-2x=5-6

-x=-1    (-1)

x=1

1+y=5

y=5-1

y=4

Par ordenado (1,4)

b) x+2y=1

2x-y=11

x+2y=1

x=1-2y

2.(1-2y)-y=11

2-4y-y=11

-5y=11-2

-5y=9

-y=9/5

y=-9/5

x+2.(-9/5)=1

x-18/5=1

x=1+18/5

x=(5+18)/5

x=23/5

Par ordenado (23/5,-9/5)

c) x+3y=5

x-y=-3

x+3y=5

x=5-3y

5-3y-y=-3

-3y-y=-3-5

-4y=-8

-y=-8/-4    (-1)

y=8/4

y=2

x-2/4=-3

(4x-2)/4=-3

x-2=-3

x=-3+2

x=-1

Par ordenado (-1,2)