An alternating series

converges if

is monotonic and

as

. Here

.
Let

. Then

, which is positive for all

, so

is monotonically increasing for

. This would mean

must be a monotonically decreasing sequence over the same interval, and so must

.
Because

is monotonically increasing, but will still always be positive, it follows that

as

.
So,

converges.
Yes and opposite and an absolute value of an integer will be the same.
He circumference of a circle<span> is equal to the diameter times pi. So, let's look at </span>what happens<span> if you double the </span>radius<span> of a </span>circle<span> -- say from 2 to 4. The area will go from 12.56 to 50.24. This means that it has </span>quadrupled<span>.</span>
1.) -15.9, -15.2, -3.6, 3.6
2.) second one is already correct
3.)-2.3, -2.03, 2.03, 3.0
All of the shown choices, also every opposite angles are equal.