1.

For the relation R1 defined on R by the rule (a, b) R1 1 + ab > 0. Prove that : (a, b) R1 and (b,c) R1 (a, c) R1 is not true for all a, b, c R.

Answer»

To prove : (a, b) R1 and (b,c) R1 (a, c) R1 is not true for all a, b, c R. 

Given,

R1 = {(a, b): 1 + ab > 0} 

Let a = 1, b = - 0.5, c = - 4 

Here, 

(1, -0.5) R1 

[∵ 1+(1×-0.5) = 0.5 > 0] 

And, 

(-0.5, -4) R1 

[∵ 1+(-0.5×-4) = 3 > 0] 

But, 

(1, -4) ∉ R1 

[∵ 1+(1×-4) = - 3 < 0] 

∴ (a, b) R1 and (b,c) R1 (a, c) R1 is not true for all a, b, c R 

Hence Proved.

NOTE : 

Here R1 is a relation whereas R denotes a real number.



Discussion

No Comment Found

Related InterviewSolutions