### Home > CCG > Chapter 4 > Lesson 4.2.2 > Problem4-73

4-73.

Write the first four terms of each of the following sequences. Homework Help ✎

1. $a_n=3·5^{n−1}$

Substitute the number of the term for $n$. For example, replace the $n$ with $1$ to find the first term.

1. $a_1=10$$a_{n+1}=−5a_n$

The first term is given. Use $(n=1)$ in the second part of the formula to find the second term.

$a_{(1+1)}=−5(a_1)\\\quad\ \ a_2 = −5(10)\\\quad \ \ a_2 = −50$

Use the answer for $a_2$ to find the third and fourth terms.

$10$, $−50$, $250$, $−1250$