Answer:
B(7,10)
Step-by-step explanation:

I guess the series is

We have

Recall that

In our limit, we have



which is greater than 1, which means the series is divergent by the ratio test.
On the chance that you meant to write

we have


which is less than 1, so this series is absolutely convergent.
Answer:
5
Step-by-step explanation:
We know that 13 is the hypotenuse. With this we can use the Pythagorean Theorem to solve this problem.
Let the third side be x.
13^2=12^2+x^2
169=144+x^2
169-144=x^2
25=x^2
x=5
Solved.
I agree it is one and I used this calculator called MathPapa that can help with algebra you should try it. It is free.