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:

7(200 + 50 + 6) = (7 x 200) + (7 x 50) + (7 x 6) = 1,400 + 350 + 42 = 1,792
She walked 3 Miles Per Hour each minute
Number one. 897 2. Eight hundred eighty four and fourth seven hundredths. Number three. 17.818. 4. Two thousand forty four and four tenths. Number five. 22.766 6. Twelve thousand five hundred and twelve Number seven. 23.62
w - width
2w + 5 - length
w + w + (2w + 5) + (2w + 5) = 6w + 10 - perimeter
34 cm - perimeter
The equation:
6w + 10 = 34 <em>subtract 10 from both sides</em>
6w = 24 <em>divide both sides by 6</em>
w = 4 cm
2w + 5 = 2(4) + 5 = 8 + 5 = 13 cm
<h3>Answer: Width = 4cm, Length = 13cm</h3>