First, note that 
Then use the formula for the sum of perfect cubes:
Therefore,
The quadratic trinomial 
couldn't be factored anymore, so the expression 
has two factors 
and 
Answer: correct choice is A.
Mean means average, so you would add the numbers up and divide by the amount of numbers in the set.
No. It's the ratio of 1,289 to 100 .
Also, it can be written as a fraction with whole numbers
on top and bottom, like this: 1289 / 100 .
Also, it can be written down on paper completely, using
digits and a decimal point or fraction bar. (You did that.)
Any one of these three facts makes it a rational number.
