One year after sarah started a new job, she had $1200 in her savings account. each year, she added $900 more to the savings account. what function, written in sequence notation, models sarah’s savings account balance n years after starting her new job? an=300n+1200 an=900n+300 an=300n+900 an=900n+1200

an=900n+300

Step-by-step explanation:

took test

Step-by-step explanation:

we are given

One year after Sarah started a new job, she had $1200 in her savings account

so, first term is 1200

Each year, she added $900 more to the savings account

so, common difference is 900

Since, it is arithematic sequence

so, we can use nth term formula

now, we can plug values

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional