Processing math: 100%
Home / Aptitude Tests / Further Mathematics / A binary operation *...
A binary operation * is defined on the set of real numbers, ...

A binary operation * is defined on the set of real numbers, R, by xy=x+yxy. If the identity element under the operation * is 0, find the inverse of xR.

A.

x1x,x1

B.

11x,x1

C.

11x,x1

D.

x1x,x1

Correct answer is A

xy=x+yxy

Let x1 be the inverse of x, so that

xx1=x+x1x(x1)=0

x+x1x(x1)=0x(x1)x1=x

x1(x1)=xx1=xx1

= x(1x)=x1x,x1