Consider the operators โ and โก defined by ๐ โ ๐ = ๐ + 2๐, ๐โก๐ = ๐๐,โฆ
2024
Consider the operators โ and โก defined by ๐ โ ๐ = ๐ + 2๐, ๐โก๐ = ๐๐, for positive integers. Which of the following statements is/are TRUE?
- A.
Operator โ obeys the associative law
- B.
Operator โก obeys the associative law
- C.
Operator โ over the operator โก obeys the distributive law
- D.
Operator โก over the operator โ obeys the distributive law
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Correct answer: B, D
Correct statements and why:
Operator โก obeys the associative law: (a โก b) โก c = (ab)c = a(bc) = a โก (b โก c).
Operator โก over the operator โ obeys the distributive law: a โก (b โ c) = a(b + 2c) = ab + 2ac, and (a โก b) โ (a โก c) = (ab) โ (ac) = ab + 2ac, so they are equal.
Why the other statements are false:
Operator โ is not associative: (a โ b) โ c = a + 2b + 2c, while a โ (b โ c) = a + 2b + 4c, so they differ in general. Example: with a = b = c = 1, (1 โ 1) โ 1 = 5 but 1 โ (1 โ 1) = 7.
โ does not distribute over โก: a โ (b โก c) = a + 2(bc) whereas (a โ b) โก (a โ c) = (a + 2b)(a + 2c), which are not equal in general. Example: a = b = c = 1 gives 3 on the left and 9 on the right.
Final answer: The true statements are those asserting that multiplication (โก) is associative and that multiplication distributes over โ.
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