Let a, b, c, and d be distinct real numbers such that
a = sqrt(4 + sqrt(5+a))
b = sqrt(4 - sqrt(5+b))
c = sqrt4 + sqrt(5-c))
d = sqrt4 - sqrt(5-d)) Compute abcd.
The solutions are 2.2192, 1.33938, 1.09044, and 2.4682, and their product is 8.
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