Mrs. fisher has 91 watches on display at her store. she says she can arrange them into rows and colums without any watch left over. mr. fisher says she can only make 1 row with all 91 watches who is correct? explain.

This is a question of whether 91 is a prime number or not. And it is not so Mrs. Fisher is right, you can arrange them in 7 rows and 19 columns or vice versa. 7 and 13 are factors of 91.

step-by-step explanation:

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for