Question

$x - y = 7 \\ 3x - y = 9$
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Answer 1

Hello !!

You can solve this question with this method.

THE LINEAR SISTEM.

x - y = 7

3x - y = 9

Isolate (x) in the first equation.

x = 7 + y

Isolate (x) in the second equation.

x = (9 + y)/3

Make the comparison.

7 + y = (9 + y)/3

(7 + y)/1 = (9 + y)/3

1(9 + y) = 3(7 + y)

9 + y = 21 + 3y

y - 3y = 21 - 9

-2y = 12

y = -6

Now, you find the solution for (x).

x - y = 7

x - (-6) = 7

x + 6 = 7

x = 7 - 6

x = 1

Final result : the solution for (x) is 1 and the solution for (y) is -6.

I hope I have collaborated !