Respuesta :

eunice1234

Answer: 20

Step-by-step explanation:

x+y=5

x-y=4

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x+y=5

x=4+y

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(4+y)+y=5

4+y+y=5

 4+2y=5

      2y=1

        y=0.5

        x=4.5

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x²-y²=(4.5)²-(0.5)²=20.25-0.25=20