If {X: 2 d- x d- 19; X integer} and 7 + x = 4 (mod 9), find the highest value of x
- 2
- 5
-
15
- 18
The correct answer is: C
Explanation
use trial and error method,
By substituting any of x = 2, 5, 15, 18 into 7 + x = 4 (mod 9)
any value of x that gives 7 + x = 4 (mod 9) is the correct value of x
In this case, x = 15.