JEE Main 2026 Mathematics question
The value of 1³−2³+3³−…+15³ is:
Answer: (B)
Solution
The sum is Σ(odd n≤15)n³ − Σ(even n≤14)n³ = (1+27+125+343+729+1331+2197+3375) − 8(1+8+27+64+125+216+343) = 8128 − 6272 = 1856.
The value of 1³−2³+3³−…+15³ is:
The sum is Σ(odd n≤15)n³ − Σ(even n≤14)n³ = (1+27+125+343+729+1331+2197+3375) − 8(1+8+27+64+125+216+343) = 8128 − 6272 = 1856.