Question

Please evaluate the equation​

Answer 1

Explanation:

`= \sum \limits_(n = 1)^(7) ( - 2. {6}^(n - 1) )`

`= \sum \limits_ {n = 1}^{n_{ \text{max}}} (a_1. {r}^(n - 1) )`

`\:`

`a_1 = - 2`

`n = 7`

`r = 6 \to r >1`

`\:`

• Find S7.

`s_n = a_1.( \frac{ {r}^(n) - 1}{r - n} )`

`s_7 = - 2.( \frac{ {6}^(7) - 1 }{6 - 1} )`

`s_7 = - 2.( (279.936 - 1)/(5) )`

`s_7 = - 2.( (279.935)/(5) )`

`s_7 = - 2 \: . \: 55.987`

`s_7 = - 111.974`

The answer is B.