[email protected] , ответ добавлен 04.04.2018 в 16:22

1) 
4, 12, 36
b1 = 4
b2 = 12
q = b2/b1 = 12/4 = 3

bn = b1*q^(n - 1) = 4*3^(n - 1) = 4/3*4^n

2)
4, - 1, 1/4
b1 = 4
b2 = - 1
q = b2/b1 = - 1/4

bn = 4*(-1/4)^(n - 1) = - 16*(-1/4)^n

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