Philip P. answered 11/23/18
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a-1/a = a-1·a-1 = a-2 = 1/a2 = 7, so a2 = 1/7 and a4 = (1/7)2 = 1/49
(a4+1)/a4 = a4/a4 + 1/a4 = 1 + (1/(1/49)) = 1 + 49 = 50