Ok so to find the ratio just do 12/16 = 3/4. that's your common ratio.
The formula for sum of infinite :
a / (1 - r)
a is the first term and r is the ratio
which is
16 / (1 - (3/4))
which is
16 / (1/4)
16 * 4
which is 64
Answer:

Step-by-step explanation:
By definition, we can write ln instead of log. WHEN??
Whenever the base of the logarithm is the number "e".
Hence, when we have:

We can write it in shortcut as:

Hence, ln x can also be written as 
Fourth answer choice is right.
The equation factors as
.. (x +3)(x +4) = 0
By the zero-product rule, the roots are
.. x1 = -4
.. x2 = -3