Answer:
The 7th term of given sequence is: 448
Step-by-step explanation:
Given sequence is:
7,-14,28,-56
Here
a1 = 7
a2 = -14
a3 = 28
First of all we have to find the common ratio. The common ration is the ratio between two consecutive terms of a geometric sequence and is same for all consecutive terms of a geometric sequence.
So,
[tex]r = \frac{a_2}{a_1} = \frac{-14}{7} = -2\\r = \frac{a_3}{a_2} = \frac{28}{-14} = -2\\[/tex]
The common ratio is -2.
The general formula for geometric sequence is given as:
[tex]a_n = a_1r^{(n-1)}[/tex]
Putting values
[tex]a_n = 7.(-2)^{n-1}[/tex]
For 7th term, putting n=7
[tex]a_7 = 7*(-2)^{7-1}\\= 7 * (-2)^6\\= 7 *64\\= 448[/tex]
Hence,
The 7th term of given sequence is: 448
