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The value of \({1}^{3}-{2}^{3}+{3}^{3}-\ldots +{15}^{3}\) is: [JEE Main 2026, 6 Apr (Shift 1)]

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The value of \({1}^{3}-{2}^{3}+{3}^{3}-\ldots +{15}^{3}\) is:

[JEE Main 2026, 6 Apr (Shift 1)]

a

\(1706\)

b

\(1856\)

c

\(1982\)

d

\(2403\)

✓ Correct answer: b)

\(1856\)

Explanation

\(S=1^3-2^3+3^3-\ldots+15^3\)

\(=\left(1^3+2^3+\ldots+15^3\right)-2\left(2^3+4^3+\ldots+14^3\right)\)

\(=\left(1^3+2^3+\ldots+15^3\right)-2^4\left(1^3+2^3+\ldots+7^3\right)\)

\(=\left[\frac{15 \times 16}{2}\right]^2-16\left[\frac{7 \times 8}{2}\right]^2\)

\(=14400-16\times 784\)

\(=14400-12544\)

\(=1856\)

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