Question

13(b). An operation (*) is defined on the set R of real numbers by m(*)n = −n/(m²+1), where m,n∈R. If −3,−10∈R, show whether or not (*) is commutative.

Accepted Answer

m*n = −n/(m²+1). Test with m=−3, n=−10:
m*n = −(−10)/((−3)²+1) = 10/10 = 1
n*m = −(−3)/((−10)²+1) = 3/101 ≈ 0.0297
Since m*n ≠ n*m (1 ≠ 0.0297), the operation (*) is NOT commutative.

WAEC Mathematics 2014 Theory — Question 23

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