If x is a rational number and y is an irrational number, then-
A. Both x + y and xy are necessarily rational
B. Both x + y and xy are necessarily irrational
C. xy is necessarily irrational, but x + y can be either rational or irrational
D. x + y is necessarily irrational, but xy can be either rational or irrational
Answer: Option D
Solution(By Examveda Team)
(a) Let x = 0 and y = $$\sqrt 2 $$Then, x is rational and y is irrational.
∴ x + y = 0 + $$\sqrt 2 $$ = $$\sqrt 2 $$ , which is irrational
Thus, x + y is not rational
(b) Let x = 0 and y = $$\sqrt 2 $$
Then, x is rational and y is irrational
∴ xy = 0 × $$\sqrt 2 $$ = 0, which is rational
Hence, xy is not irrational
(c) As shown in (B), xy is not necessarily irrational
(d) x + y is necessary irrational. But xy can be either rational or irrational.
Hence, (D) is true.
Related Questions on Number System
Three numbers are in ratio 1 : 2 : 3 and HCF is 12. The numbers are:
A. 12, 24, 36
B. 11, 22, 33
C. 12, 24, 32
D. 5, 10, 15
Join The Discussion