Question

Compute the sums below. (Assume that the terms in the first sum are consecutive terms of an arithmetic sequence.)9 +13 + 17+ ... + 373 =121Σ (-3k-5) = 0k = 1XS

Answer 1

Let's find the expression for the first sequence

Now we need to know what positions have 373 in the sequence, for this we need to replace the number in the equation and find n :

Now we can use the formula to find the sum of all the terms:

The answer for the first sum is 17572

Now let's calculate the second sum:

Now we can use the formula to find the sum of the 121 first terms

The answer for the second sum is -22748.