Which of the following sequences is not arithmetic? 2, 4, 6, 8, ...
1, 2, 3, 4, ...
1, 4, 9, 16, ...
0, -2, -4, -6, ...

Find the value of the cosine for angle a

12. the amount of money in a bank account decreased by 21.5% over the last year. if the amount of money at the beginning of the year is represented by ‘n', write 3 equivalent expressions to represent the amount of money in the bank account after the decrease?

How do you use the elimination method for this question? explain, because i really want to understand!