hi, i've been working on my homework that's due tomorrow, and i'm nearly done, but these are the only problems i've had trouble with. all questions are non-calculator, so steps would be appreciated:

The graph of the function f(x)= 3e^x-4 has an asymptote of

a) x= -4

b) x= 3

c) y= -4

d) y= 3

e) y=x

What are the steps for solving this? i haven't been given a formula. isn't the first step to find ln of the equation? how do i go about doing that?

Radioactive substance decreases by 10% per hour. if there were 64 grams of the substance at time t=1, which of the following exponential functions models the amount, R, in grams of the substance as a function of the time, t, in hours?

a) R= 54(1.10)^t

b) R= 60(1.10)^t

c) R= 48.6(1.10)^t

d) R= 54(.90)^t

e) R= 60(.90)^t

The equation for the decay function is A(t)= a(1-r)^t, I believe. I came up with 1= 54(.90)^t as my answer, so that's d, but i am not completely sure..

k(x)= 4^x, then k(x-2)=

a) 1/16(4^x)

b) 1/2(4^x)

c) 4^x-16

d) 4^x-2

e) (1/16)^x

I know that since it is not asking for k(x)-2, d is definitely not a correct answer. k(x-2)= 4^(x-2), so what are the next steps??

I have this table of values:

x | -1 | 0

f(x)|-6 | -2

I need to make it into an exponential function. What are the steps I should take?

Choices are:

a) y= 2(-3)^x

b) y= -2(-3)^x

c) y= -2(3)^-x

d) y= 1(-6)^x

e) y= -1(6)^x

Population of students at school is modeled by function P(t)= 500(1.12)^t, where t is the number of years since 1995. With this model, by what % is the popilation of the school changing each year?

a) 400%

b) 112%

c) 88%

d) 12%

e) 4%

i'm guessing d, 12%, since this seems to be following the growth formula A(t)= a(1+r)^t, am I right?

i hope you can help, thank you!!!