13-1

This week in advanced math we took a test on chapter 11 which involved lots of formulas. For the most part the test were easy as long as you knew the formulas. But at the end of the week we learned 13-1 which involves number sequences. There's arithmetic sequence, a sequence where the same number is added each time. And geometric, a sequence where the same number is multiplied each time.

Formulas:

arithmetic- tn=t1 + (n-1)d

geometric- tn= t1 * rn^-1

I don't really understand this yet so I don't know if this is right.

Ex.

How many multiples of 5 are there between 25 and 75

30, 35 , ... 75

d=9

75= 25 + (n-1)(9)

50=(n-1)(9)

49=(n)(9)

n=7