Question

Решите систему уравнений : { 4(x-y)-3xy=-14 7x+4xy-7y=31

Answer 1

4(x-y)-3xy=-14

7(x-y)+4xy=31

 

x-y=t

xy=s

 

4t-3s=-14  х4         16t-12s=-56

7t+4s=31   х3         21t+12s=93

                              37t=37

7+4s=31  4s=24  s=6

 

x-y=1

xy=6

 

x=2  y=3

x=-2 y=-3

Answer 2

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