(3)

We have the quadratic:

For both roots to be real, distinct, and negative, we can also use Vieta's formulas:

Sum of roots:

Since both roots are negative,

Product of roots:

Since both roots are negative, (product of two negatives is positive)

So (already satisfied for )

Discriminant : Already calculated

Now combine all conditions:

(sum negative)

(from discriminant)

Only integer value in this range is .

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