i'm supposed to write the following intervals as sets indescriptive form:
a. (t, infinity), t a fixed real number
b. (0, 1/n), n a fixed natural number

i think it is:
a. (t, infinity) = {x: t < x < infinity}
b. (0,1/n) = {x: 0 < x < 1/n}
is this correct?
also, how do you indicate that t is a fixed realnumber and n a fixed natural number?

Is correct.

Step-by-step explanation:

If you don't write the n and t in the left part of the set (before the : ) we assume that are fixed.

(t, infinity) = {}

(0,1/n) =  {}

3, 12, 48, 384, 1536, 6144, 24576, 98304

step-by-step explanation:

just keep timing it by 4.

e^-kt = n/n0 = 0.79  

-kt = ln 0.79  

t = - ln 0.79/0.0001  

= 2357 years

step-by-step explanation: