JEE Main 2026 Mathematics question
Let α = 3 + 4 + 8 + 9 + 13 + 14 + … upto 40 terms. If is a root of the equation x² + x − 2 = 0, β ∈ (0, π/2), then sin²β + 3cos²β is equal to:
Answer: (A)
Solution
Group the terms into 20 pairs (3+4), (8+9), (13+14), …; the pair sums 7, 17, 27, … form an A.P. with a=7, d=10, so
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