Question

5 x + y=7 /3x-y= -1
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Answer 1

5x+y=7

3x-y=-1

_____________

5x+y=7 => y=5x-7

3x-y=-1 => 3x-5x-7=-1

_______________

-2x-7=-1

-2x=7

-x=7:(-2)

-x=-3,5

x=3,5

3x-y=-1

3×3,5-y=-1

10,5-y=-1

y=1-10,5

y=-9,5

_____________

VERIFICARE:

5x+y=7

5×3,5+(-9,5)

17,5-9,5

7=7 adevărat