Answer:
1st problem: b) 
2nd problem: c) 
Step-by-step explanation:
1st problem:
The formula/equation you want to use is:

where
t=number of years
A=amount he will owe in t years
P=principal (initial amount)
r=rate
n=number of times the interest is compounded per year t.
We are given:
P=2500
r=12%=.12
n=12 (since there are 12 months in a year and the interest is being compounded per month)

Time to clean up the inside of the ( ).


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2nd Problem:
Compounded continuously problems use base as e.

P is still the principal
r is still the rate
t is still the number of years
A is still the amount.
You are given:
P=2500
r=12%=.12
Let's plug that information in:
.
Answer:
11x+2
Step-by-step explanation:
Perhaps the most concise way to factor is by "completing the square" which is how the quadratic formula is derived...
x^2+6x+8=0 move constant to other side, subtract 8 from both sides
x^2+6x=-8, halve the linear coefficient, square it, then add that to both sides, in this case (6/2)^2=3^2=9
x^2+6x+9=1 now the left side is a perfect square of the form
(x+3)^2=1 take the square root of both sides
x+3=±√1 subtract 3 from both sides
x=-3±√1
x=-3±1
x=-4 and -2
Since the zeros occur when x=-4 and -2 the factors of the equation are:
(x+2)(x+4)