Arithmetic Sequences

a, b, c, d,... is an arithmetic sequence if

• There's a common differnce between the elements

• There's a common ratio between the elements

• They start with one

• All numbers are positive

The common difference in an arithmetic sequence can be positive, negative or fractional

• True

• False

Is this sequence arithmetic:

-7, -12, -17, -22

• Yes

• No

Is this sequence arithmetic:

2, 4, 8, 16

• Yes

• No

What is the common difference of the arithmetic sequence:

5, 6.25, 7.5, 8.75

• 1.25

• It's not an arithmetic sequence

• 1.5

• 1

What is the common difference of the arithmetic sequence:

18, 15, 12, 9

• -3

• 3

• 4

• -2

 $U_n=10n-4$  
This is the...

• explicit formula

• exquisite formula

• recursive formula

• repulsive formula

 $U_n=U_{n-1}+8$  
This is the...

• explicit formula

• exquisite formula

• recursive formula

• repulsive formula

A correct formula for the arithmetic sequence 12, 19, 26, 33 is

• $U_n=U_{n-1}+7$

• $U_n=12\left(n-1\right)+7$

• $U_n=U_{n+1}-7$

• $U_n=7\left(n-2\right)+12$

A correct formula for the arithmetic sequence 1, -4, -9 is

•  $U_n=U_{n-2}-5$ 

•  $U_n=-5\left(n-1\right)+1$ 

•  $U_n=U_{n+1}+5$ 

•  $U_n=1\left(n-1\right)-5$