Question
If is real and , then possible values of include
Official answer and solution
- Official answer
- D
- From
- Official GATE 2014 answer key
Solution
Solve the absolute value quadratic equation for real x and evaluate the target expression for each valid root.
Given .
-
Analyze the Quadratic:
For all real , , which implies .
Because the term inside the absolute value is strictly positive, the equation simplifies to: -
Solve for :
-
Evaluate Target Expression :
- Case 1 ():
- Case 2 ():
- Case 1 ():
-
Thus, the possible values are and (option D).
D
Missing the case x = -2 or making sign errors when substituting negative values.
The answer is the one in the official GATE answer key. The solution is this site's own explanation.
Source
- Paper
- GATE 2014 Computer Science and Information Technology (CS) Session 2
- Question
- 8 of 65, printed as GA Q.8
- Section
- General Aptitude
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