Question

Let ‘*’ be a binary operation on N defined by a*b=a-b+ab^2, then find 4*5.

(a) 9

(b) 88

(c) 98

(d) 99

I have been asked this question in examination.

The origin of the question is Binary Operations topic in division Relations and Functions of Mathematics – Class 12

Answer 1

Right answer is (d) 99

Explanation: The binary operation is defined by a*b=a-b+ab^2.

∴4*5=4-5+4(5^2)=-1+100=99.