Question

For the following geometric sequence find the explicit formula: {-1, 3, -9,...}

Answer 1

multiplies by -3 every time

Answer 2

Answer:

$a_{n}$ = - 1 $(-3)^{n-1}$

Step-by-step explanation:

The explicit formula for a geometric sequence is

$a_{n}$ = a $(r)^{n-1}$

where a is the first term and r the common ratio

Here a = - 1 and r = 3 ÷ - 1 = - 3 , thus explicit formula is

$a_{n}$ = - 1 $(-3)^{n-1}$