The numerator is the number of equal parts
For a quadratic of the form

, we have the quadratic formula

,
where a is the coefficient (number before the variable) of the squared term, b is the coefficient of the linear term, and c is the constant term.
So, given

, we can get that

, and

. We substitute these numbers into the quadratic formula above.





This is our final answer.
If you've never seen the quadratic formula, you can derive it by completing the square for the general form of a quadratic. Note that the

symbol (read: plus or minus) represents the two possible distinct solutions, except for zero under the radical, which gives only one solution.
Answer:
the common difference is 5.4 and yes, this is an arithmetic sequence
Step-by-step explanation:
Each new term is derived by adding 5.4 to the previous term:
2.1 + 5.4 = 7.5,
7.5 + 5.4 = 12.9,
and so on,
so the common difference is 5.4 and yes, this is an arithmetic sequence.
The question was worded weird but if it’s asking for 1/4 divided by 8 then the answer is 2