Suppose is any integer such that the equation has no real roots and the equation has two distinct real roots for . Then, the number of possible values of is
Suppose is any integer such that the equation has no real roots and the equation has two distinct real roots for . Then, the number of possible values of is
Solution
We need to find integer values of such that:
- has no real roots
- has two distinct real roots
For any quadratic equation , the discriminant tells us about the nature of roots:
If : No real roots
If : One repeated real root
If : Two distinct real roots
For :
Here, , ,
Discriminant:
For no real roots:
Since , we get:
Since must be an integer:
For :
Here, , ,
Discriminant:
For two distinct real roots:
When , we have:
This absolute value inequality gives us two cases:
Case 1:
Case 2:
So from condition 2: or
We need values of that satisfy both conditions:
Condition 1: (integers)
Condition 2: or
The range doesn't overlap with
So we only consider combined with
This gives us: where is an integer.
Therefore:
The number of possible values of is 9.
Note that would make the second equation have exactly one repeated root (since ), which violates our "two distinct roots" condition.
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