Question

a)2x+y=10 x+y=6
b)3x-5y=-8 2x+3y=2
c)2x+y=4 3x-y=2
d)4x-3y=5 3x+y=7

Answer 1

A)

2x+y=10

x+y=6 (-1)

2x + y = 10

- x - y = - 6 (+)

-------------------

x = 4

x + y = 6

4 + y = 6

y = 6 - 4

y = 2

b)

3x-5y=-8 (-2)

2x+3y=2 (3)

-6x + 10y = 16

6x + 9y = 6 (+)

----------------------

19y = 22

y = 22/19

2x + 3y = 2

2x + 3.22/19 = 2

2x + 66/19 = 2

2x = 2 - 66/19

19.2x/19 = (19.2 - 66)/19

38x = 38 - 66

38x = - 28 (:2)

19x = - 14

x = - 14/19

c)

2x+y=4

3x-y=2 (+)

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5x = 6

x = 6/5

2x + y = 4

2.6/5 + y = 4

12/5 + y = 4

(12 + 5y)/5 = 4.5/5

12 + 5y = 20

5y = 20-12

5y = 8

y = 8/5

d)

4x-3y=5

3x+y=7 (3)

4x - 3y = 5

9x + 3y = 21 (+)

------------------------

13x = 26

x = 26/13

x = 2

4x - 3y = 5

4.2 - 3y = 5

8 - 5 = 3y

3 = 3y

3y = 3

y = 3/3

y = 1