Respuesta :

Answer:

Step-by-step explanation:

x + y = 18

y = 18 - x

xy = 72

x(18 - x) = 72

-x² + 18x = 72

0 = 72 - 18x + x²

x = (18 ± √(18² - 4(1)(72))) / (2(1))

x = (18 ± 6)/2

x = 12

x = 6

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