Question

If R = {(x,y) | x $\in$ N, y $\in$ N, x + 3y = 12} then $R^{-1}$ is

• A. {(1,9), (2, 6),(3, 3)}
• B. {(3,1), (2, 4),(3, 6)}
• C. {(3,3), (2, 6),(1, 9)}
• D. {(1,3), (1, 6),(1, 9)}

Answer 1

The correct option is C

{(3,3), (2, 6),(1, 9)}

x + 3y = 12

x = 3, y = 3

x = 6, y = 2

x = 9, y = 1

R = {(3,3),(6,2),(9,1)}

$R^{-1}$ = {(3,3)(2,6)(1,9)}