If [z] denotes the least integer greater than or equal to z and [z2] =...
Given:
- The function [z]
- [z2] = 2
To find: Can [z] be {2, 1, -2}?
Approach:
- To find which values of [z] are possible and which are not, we need to first know the range of possible values of z. Once we know what z can be, we’ll be able to find what [z] can be.
- We’ll get an idea of the possible values of z from the fact that [z2] = 2
Working Out:
- [z2] = 2
- This means, the least integer that is greater than or equal to z2 is 2.
- So, the value of z2 must be equal to 2 or must lie between 1 and 2 (because if z2 is less than 1 then [z2] would be 1 or less and not 2)
- The above inequality contains 2 inequalities: z2 > 1 AND z2 ≤ 2
- So now, we’ll solve these inequalities one by one, and then find the values of z that satisfy both these inequalities
- Solving z2 > 1
- This means, z < - 1 or z > 1 . . . (1)
- The gray zones in the above figure represent the overlap zones, that is, those values of z that satisfy both the inequalities
- So, either -√2 ≤ z < -1 or 1 < z ≤ √2
Thus, we see that [z] is either equal to -1 or equal to 2. Out of the 3 given values, only value I (which is 2) is therefore possible.
Looking at the answer choices, we see that the correct answer is Option A
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If [z] denotes the least integer greater than or equal to z and [z2] =...
Understanding the Problem
To solve the problem, we need to analyze the condition given: [z^2] = 2, where [z] denotes the least integer greater than or equal to z. This means that the smallest integer greater than or equal to z^2 is 2.
Analyzing [z^2] = 2
This implies:
- 2 ≤ z^2 < 3="" from="" this="" inequality,="" we="" can="" derive="" the="" possible="" values="" of="" z:="" -="" taking="" the="" square="" root="" gives:="" √2="" ≤="" z="" />< √3="" or="" -√3="" />< z="" ≤="" -√2="" the="" numerical="" approximations="" for="" these="" roots="" are:="" -="" √2="" ≈="" 1.41="" -="" √3="" ≈="" 1.73="" thus,="" we="" can="" summarize="" the="" ranges="" for="" z="" as:="" -="" 1.41="" ≤="" z="" />< 1.73="" or="" -1.73="" />< z="" ≤="" -1.41="" />Determining Possible Values of [z]
Now, let's check the implications for [z]:
- For 1.41 ≤ z < 1.73:="" -="" the="" least="" integer="" greater="" than="" or="" equal="" to="" z,="" [z],="" can="" only="" be="" 2="" (since="" 1="" />< z="" />< 2).="" -="" for="" -1.73="" />< z="" ≤="" -1.41:="" -="" the="" least="" integer="" greater="" than="" or="" equal="" to="" z,="" [z],="" can="" only="" be="" -1="" (since="" -2="" />< z="" ≤="" -1).="" />Evaluating the Options
Now, let's evaluate the options:
I. 2: Possible since z falls within 1.41 ≤ z < 1.73.="" ii.="" 1:="" not="" possible="" since="" there="" are="" no="" z="" values="" that="" yield="" [z]="1." iii.="" -2:="" not="" possible="" since="" there="" are="" no="" z="" values="" that="" yield="" [z]="-2." />Final Conclusion
The only valid value for [z] that meets the condition [z^2] = 2 is:
- Option I (2) is correct.
Thus, the correct answer is option 'A'.