Question

11(c). An operation ⊙ is defined on the set X={1,3,5,6} by m⊙n = m+n+2(mod7), where m,n∈X. (i) Draw a table for the operation. (ii) Using the table, find the true set of: I. 3⊙n=3; II. n⊙n=3.

Accepted Answer

(i) Constructing the table for m⊙n=(m+n+2)mod7 for all combinations of m,n∈{1,3,5,6} gives the operation table shown in the solution.
(ii)(I) From the table, 3⊙n=3 has the true set {5}.
(II) From the table, n⊙n=3 has no solution in the set, so the truth set is ∅ (empty set).

WAEC Mathematics 2015 Theory — Question 20

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