Sets B = {x : x > 15 and x < 5}, C = {x : x − 5 = 0}, E = {x : x is an integral positive root of x² − 2x − 15 = 0}. Identify the only equal pair among A = {0}, B, C, D = {x : x² = 25}, E.
AB = D
BA = B
CC = E
DD = E
Answer & Solution
Correct answer: C. C = E
B = ∅ (no x both > 15 and < 5). C = {5}. D = {-5, 5}. E: x² − 2x − 15 = 0 → x = 5, -3; positive integral root is 5, so E = {5}. Hence C = E.
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