The value of (1³ +2³ +3³ + ... +15³) - (1+2+3+...+15) = ...... is :
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Answer: 14280
Step-by-step explanation:
We have to find 1³ + 2³ + 3³....... 15³
Hence, let n = 15.
Therefore, [n² × (n+1)²]/4
:. [15² × (16)²]/4
[225 × 256]/4
57600/4
14400
Then we have to find 1 + 2 + 3...... 15
Hence let n again be 15.
Therefore, n(n+1)/2
:. 15 × 16/2
240/2
120
So, 14400 - 120 = 14280
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