Respuesta :

caylus

Answer:

Step-by-step explanation:

[tex]u_1=4\\u_2=20=4*5\\u_3=100=20*5=4*5^2\\u_4=500=100*5=4*5^3\\\\\boxed{u_n=4*5^{n-1}}\\[/tex]

The sequence is geometric with first term =4 and common factor=5

Answer:

Rule is 4(5)^(n-1).

a7 = 62500.

Step-by-step explanation:

This is a geometric sequence with a1 = 4 and r = 20/4 = 5.

a7 is 4(5)^(7-1)

= 4 * 5^6

= 62500.