It is given that \([x] <= x\) & \( [n/4] - [n/9] = 2\)
We have to find the minimum possible value of \(n\).
Let \([n/4] = a\); \([n/9] = b\),
we have \(a - b = 2 \) ~ (1)
Now we know for the greatest integer function, \([x]<= x < [x] + 1\);
Substituting we get,
\(a <= n/4 < a + 1\); this converts to,
\(4a <= n < 4a + 4 \) ~ (2)
Also,
\(b <= n/9 < b + 1\)
\(9b <= n < 9b + 9\) ~ (4)
From (1) we also have \(a = b + 2\),
Substituting this in (3) we get,
\(4b + 8 <= n < 4b + 8 + 4\)
\(4b + 8 <= n < 4b + 12 \)~ (5)
Now we have two distinct equations for n in terms b; (4) & (5),
\(9b <= n < 9b + 4\)
\(4b + 8 <= n < 4b + 12\)
Now it is mentioned that \(n\) is a positive integer so \(b\) must be a non-negative integer.
To find the minimum possible value, we have to substitute the smallest possible value for \(b\) that is non-negative, which is 0.
We have,
\(9b <= n < 9b + 9\)
\(4b + 8 <= n < 4b + 12\), substituting \(b = 0 \) we get,
\(0 <= n < 9\)
\(8 <= n < 12\)
The only values of n that satisfy both the equations should lie within the intersection of the intervals \([0, 9)\) & \([8, 12)\); That is the interval \(8 <= n < 9\)
Since n is an integer value, the only possible value that n can take is \(8\).
This is the minimum possible value for n as substituting \(b = 1\) would provide a significantly larger range with bigger values for \(n\).
Therefore, the correct option is Option B