Question

Given that$a_0=-3,a_1=5,a_2=-4,a_3=2$and$\underset{k=2}{\overset{\infty }{\sum a_k}}=7$, find the value ofrole="math" localid="1648828803227" $\underset{k=3}{\overset{\infty }{\sum a_k}}$.

Short answer

The value of$\underset{k=3}{\overset{\infty }{\sum a_k}}$is 11.

Step-by-step solution

Step 1. Given information.

Given that $a_0=-3,a_1=5,a_2=-4,a_3=2$and$\underset{k=2}{\overset{\infty }{\sum a_k}}=7$.

Step 2. Express the series in terms of known values.

Value of $\underset{k=3}{\overset{\infty }{\sum a_k}}$can be obtained as follows.

$\begin{array}{rcl}\underset{k=3}{\overset{\infty }{\sum a_k}}& =& \underset{k=2}{\overset{\infty }{\sum a_k}}-a_2\\ & =& 7-\left(-4\right)\\ & =& 7+4\\ & =& 11\end{array}$

Therefore, value of $\underset{k=3}{\overset{\infty }{\sum a_k}}$is 9.