Find the value of the speciﬁed ﬁnite sum.
-$$\text { Given } \sum _ { k = 1 } ^ { n } a _ { k } = 5 \text { and } \sum _ { k = 1 } ^ { n } b _ { k } = 7 \text {, find } \sum _ { k = 1 } ^ { n } \left( a _ { k } - 2 b _ { k } \right) \text {. }$$
A) 9
B) -19
C) -9
D) 19

Question

Quizplus · Accepted Answer

Using distributive property, we get
\begin{align*}
\sum_{k=1}^n (a_k - 2b_k) &= \sum_{k=1}^n a_k - 2\sum_{k=1}^n b_k \
&= 5 - 2(7) \
&= -9
\end{align*}

Find the Value of the Speciﬁed ﬁNite Sum A) 9 B) -19 C) -9 D) 19

Find the Value of the Speciﬁed ﬁNite Sum A) 9
B) -19
C) -9
D) 19