Mark the tick against the correct answer in the following:

Let a * b = a + ab for all a, b Q. Then,


According to the question ,


Q = { a,b }


R = {(a, b) : a * b = a + ab }


Formula


* is commutative if a * b = b * a


* is associative if (a * b) * c = a * (b * c)


Check for commutative


Consider , a * b = a + ab


And , b * a = b + ba


Both equations will not always be true .


Therefore , * is not commutative ……. (1)


Check for associative


Consider , (a * b) * c = (a + ab) * c = a+ab + (a+ab)c=a+ab+ac+abc


And , a * (b * c) = a * (b+bc) = a+a(b+bc) = a+ab+abc


Both the equation are not the same and therefore will not always be true.


Therefore , * is not associative ……. (2)


Now , according to the equations (1) , (2)


Correct option will be (B)

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