Respuesta :
Answer:
[tex] a_1 = 3 , a_2 = -9[/tex]
So then we have this:
[tex] 3 = a r^{1-1}= a[/tex]
And using the second term we have:
[tex] -9 = 3 r^{2-1}[/tex]
And solving for the value of r we got:
[tex] r = \frac{-9}{3}= -3[/tex]
So then our general expression for this geometric sequence would be:
[tex] a = 3 (-3)^{n-1} , n\geq 1[/tex]
And the best answer would be:
an = 3(−3)n − 1; all integers where n ≥ 1
Step-by-step explanation:
For this case we need to remember that the general formula for a geometric sequence is given by:
[tex] a_n = a r^{n-1}[/tex]
And for this case we have the following values for the sequence given:
[tex] a_1 = 3 , a_2 = -9[/tex]
So then we have this:
[tex] 3 = a r^{1-1}= a[/tex]
And using the second term we have:
[tex] -9 = 3 r^{2-1}[/tex]
And solving for the value of r we got:
[tex] r = \frac{-9}{3}= -3[/tex]
So then our general expression for this geometric sequence would be:
[tex] a = 3 (-3)^{n-1} , n\geq 1[/tex]
And the best answer would be:
an = 3(−3)n − 1; all integers where n ≥ 1
