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In Problems 71-82, find the sum of each sequence.

∑k3k=520

Short Answer

Expert verified

The sum of this sequence is 44000.

Step by step solution

01

Step 1. Write the given information.

The sum of sequence:

∑k3k=520

02

Step 2. Use the properties of sequence.

Using the properties of sequence:

∑k3k=j+1n=∑k3k=1n-∑k3k=1jSo,∑k3k=520=∑k3k=120-∑k3k=14

03

Step 3. Use the formula for sum of sequences of (n3 ), n - real numbers.

The formula for summation:

∑k3k=1n=13+23+...+n3⇒∑k3k=1n=n(n+1)22

So,

∑k3k=520=∑k3k=120-∑k3k=14⇒∑k3k=520=20(20+1)22-4(4+1)22⇒∑k3k=520=10×212-2×52⇒∑k3k=520=44100-100⇒∑k3k=520=44000

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