csat-suneung 2021 Q10

csat-suneung · South-Korea · csat__math-humanities 3 marks Sequences and Series Evaluation of a Finite or Infinite Sum

For two sequences $\left\{ a _ { n } \right\}$ and $\left\{ b _ { n } \right\}$, $$\sum _ { k = 1 } ^ { 5 } a _ { k } = 8 , \quad \sum _ { k = 1 } ^ { 5 } b _ { k } = 9$$ What is the value of $\sum _ { k = 1 } ^ { 5 } \left( 2 a _ { k } - b _ { k } + 4 \right)$? [3 points]
(1) 19
(2) 21
(3) 23
(4) 25
(5) 27

For two sequences $\left\{ a _ { n } \right\}$ and $\left\{ b _ { n } \right\}$,
$$\sum _ { k = 1 } ^ { 5 } a _ { k } = 8 , \quad \sum _ { k = 1 } ^ { 5 } b _ { k } = 9$$
What is the value of $\sum _ { k = 1 } ^ { 5 } \left( 2 a _ { k } - b _ { k } + 4 \right)$? [3 points]\\
(1) 19\\
(2) 21\\
(3) 23\\
(4) 25\\
(5) 27

Paper Questions

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