Solution

The correct answer is {(x1, 0.7), (x2, 0.3), (x3, 0.6)}

Key Points

The complement of a fuzzy set ( A ) is found by subtracting the membership degree of each element from 1. For fuzzy set ( A = {(x1, 0.3), (x2, 0.7), (x3, 0.4)} ), the complement ( A' ) would have elements with membership degrees calculated as follows:

• For ( x1 ), the complement membership degree is ( 1 - 0.3 = 0.7 ).
• For ( x2 ), the complement membership degree is ( 1 - 0.7 = 0.3 ).
• For ( x3 ), the complement membership degree is ( 1 - 0.4 = 0.6 ).
• So, the complement of ( A ) should be ( A' = {(x1, 0.7), (x2, 0.3), (x3, 0.6)} ).

Among the given options, Option 3 correctly represents the complement of ( A ): ({(x1, 0.7), (x2, 0.3), (x3, 0.6)})
So the correct answer is: ({(x1, 0.7), (x2, 0.3), (x3, 0.6)})