Answer:
a)
, b)
, c)
, d) 
Step-by-step explanation:
a) Let assume an initial mass m decaying at a constant rate k throughout time, the differential equation is:

b) The general solution is found after separating variables and integrating each sides:

Where
is the time constant and 
c) The time constant is:


The particular solution of the differential equation is:

d) The amount of radium after 300 years is:

3/5*3
pretend that 3 has a denominator which is 1
3/5*3/1
mutiply the numerators together
3*3= 9
mutiply the denominators together
5*1= 5
Answer:
9/5, 1.8 and 1 4/5
Answer:
36.2
Step-by-step explanation:
144.8/4 = 36.2
Answer:
2+4-21
Step-by-step explanation: