# CAT Practice : Functions

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Greater Integer Function

## Greatest Integer Function

Q.18: Find the value of x for which x[x] = 39
1. 6.244
2. 6.2
3. 6.3
4. 6.5

Choice D. 6.5

## Detailed Solution

When x = 7,
x[x] = 7 x 7 = 49
When x = 6,
x[x] = 6 x 6 = 36
Therefore, x must lie in between 6 and 7 =) [x] = 6
=) x = $\frac{45}{[x]} = \frac{39}{6}$ = 6.5

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Functions.