An ellipse uses major axis and minor axis.
The major is the larger axis and the minor is the smallest.
Since this ellipse is wider than it is tall the horizontal red line would be the major axis.
The answer is B.
Prime factorization of 160 = 2 x 2 x 2 x 2 x 2 x 5
This appears to be just an expression we are simplifying, not an equation we are solving. I THINK you are saying that the expression looks like this:

If you rationalize the denominator, you would get this expression:

which, after simplifying, looks like this:

and that's as simple as I can see that one getting. You can't factor anything out of the denominator to cancel with the numerator, so I think you're as simple as you can get there!
In normal line integration, from what I understand, you are measuring the area underneath (,)
f
(
x
,
y
)
along a curve in the -
x
-
y
plane from point
a
to point
b
.