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CBSE Class 12 Mathematics 2026 Main Paper 65/2/2 · Q171 Marksdeterminant_expansion

CBSE Class 12 Mathematics 2026 Main Paper 65/2/2 · Question 17 (Determinants)

The determinant of [[−1,−2,5],[−2,a,−1],[0,4,2a]] is −86. Find the sum of the possible a values.

✅ Step-by-Step Solution

Final Answer: −4
  1. Expansion gives −2a²−8a−44=−86, or a²+4a−21=0. Its roots 3 and −7 sum to −4.

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All Questions in CBSE Class 12 Mathematics 2026 Main Paper 65/2/2

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