Respuesta :

Answer:

x = 81

Step-by-step explanation:

y = k√x

56 = k√49

56 = k(7)

Divide both sides by 7

8 = k

k = 8

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When y = 72

72 = 8√x

Divide both sides by 8

9 = √x

Square both sides

81 = x

x = 81