Evaluate the sum.
-$\sum _ { j = 1 } ^ { 10 } ( 7 j - 5 )$

Name: Evaluate the sum. -$\sum _ { j = 1 } ^ { 10 } ( 7 j - 5 )$
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Question

Quizplus · Accepted Answer

The sum can be simplified by distributing the summation over each term: $\sum _ { j = 1 } ^ { 10 } 7j - \sum _ { j = 1 } ^ { 10 } 5$. The first part is a sum of an arithmetic series with a common difference of 7, and the second part is simply 10 times 5. Calculating each part gives $7 \times \frac{10(10+1)}{2} - 5 \times 10 = 385 - 50 = 335$.

Evaluate the Sum ∑j=110(7j−5)\sum _ { j = 1 } ^ { 10 } ( 7 j - 5 )∑j=110​(7j−5)

Evaluate the Sum $\sum _ { j = 1 } ^ { 10 } ( 7 j - 5 )$