Answer:
B.
Step-by-step explanation:

Answer:

Step-by-step explanation:
The sum you are trying to understand is this.

Remember that in general when you have a geometric series
you have that
and that equality is true as long as
.
Therefore here we have
and 
Therefore we can use the formula and

Answer:

Step-by-step explanation:
Comparing it with quadratic equation
, we get:
a = 1 . b = 4 and c = 5
So,
Discriminant = 
D = (4)²-4(1)(5)
D = 16 - 20
D = -4
Hence,
Discriminant = -4
![\rule[225]{225}{2}](https://tex.z-dn.net/?f=%5Crule%5B225%5D%7B225%7D%7B2%7D)
Hope this helped!
<h3 /><h3>~AH1807</h3>