Question

1°) Resolva os sistemas de equações abaixo utilizando qualquer método sabendo que U=IR ×IR.

a)
$2x + 3y = 2 \\ x - y = 8$
b)
$x + 2y = 3 \\ 9x - y = 2$
c)
$- 2x + y = 1 \\ y = - x - 5$
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Answer 1

a)

{2x+3y=2

{x-y=8×(3)

{2x+3y=2

+{3x-3y=24

5x=26

x=26/5

x-y=8

y=x-8 = 26/5 -8

y=(26-40)/5

y=-14/5

S={26/5,-14/5}

b)

{x+2y=3

{9x-y=2 ×(2)

{x+2y=3

+{18x-2y=4

19x=7

x=7/19

9x-y=2

y=9x-2 =9.7/19 -2

y=63/19 -2

y=(63-38)/19

y=25/19

S={7/19,25/19}

c)

{- 2x + y = 1

{y = - x - 5 ×(-1)

{-2x+y=1

+{-y=x+5

-2x=x+6

-2x-x=6

-3x=6×(-1)

3x=-6

x=-6/3

x=-2

y=-x-5

y=-(-2)-5 =2-5=-3

S={-2,-3}