Answer:

Step-by-step explanation:

Use the trigonometric identity

Then,

The sum clearly diverges. This is indisputable. The point of the claim above, that

is to demonstrate that a sum of infinitely many terms can be manipulated in a variety of ways to end up with a contradictory result. It's an artifact of trying to do computations with an infinite number of terms.
The mathematician Srinivasa Ramanujan famously demonstrated the above as follows: Suppose the series converges to some constant, call it

. Then

Now, recall the geometric power series

which holds for any

. It has derivative

Taking

, we end up with

and so

But as mentioned above, neither power series converges unless

. What Ramanujan did was to consider the sum

as a limit of the power series evaluated at

:

then arrived at the conclusion that

.
But again, let's emphasize that this result is patently wrong, and only serves to demonstrate that one can't manipulate a sum of infinitely many terms like one would a sum of a finite number of terms.
Answer:
100
Step-by-step explanation:
50+30=80
180-80=100
Hope this helped :)
In this problem, you must change the signs of everything in the parenthesis, which will come to 3x^2 + x - 5x^2 - x + 4. Add like terms, and you will end up with -2x^2 + 4, which is answer choice A. Hope this helped