The graph shows the amount of a chemical in a water sample. It is decreasing exponentially.

Find the coordinates of the points labeled \(A\), \(B\), and \(C\). Explain your reasoning. 

Graph of a function on grid, origin O. Horizontal axis, time, hours, from 0 to 8 by 1's. Vertical axis, chemical, milligrams, from 0 to 1,200 by 200's. Plotted coordinates as follows: 0 comma 1,000, 1 comma 800. The next three points labeled A, B and C, with 4 more points plotted.

The graph shows the amount of a chemical in a water sample at different times after it was first measured.

Select all statements that are true.

Graph of a function on grid, origin O. Horizontal axis, time, hours, from 0 to 6 by 0 point 5's. Vertical axis, chemical, milligrams, from 0 to 2,400 by 400's. Plotted coordinates as follows: 0 comma 2,000, 1 comma 1,000, 2 comma 500, 4 comma 250, 5 comma 125.  

The graph shows the amount of a chemical in a patient's body at different times measured in hours since the levels were first checked.

Could the amount of this chemical in the patient be decaying exponentially? Explain how you know.

Graph of a function on grid, origin O. Horizontal axis, time in hours, from 0 to 8 by 1's. Vertical axis, chemical in milligrams, from 0 to 1,200 by 200's. Labeled plotted coordinates as follows: 0 comma 1,000, 1 comma 600, 2 comma 360, with 6 additional points plotted following a similar trend.  

The height of a plant in mm is 7. It doubles each week. Select all expressions that represent the height of the plant, in mm, after 4 weeks.

The number of people who have read a new book is 300 at the beginning of January. The number of people who have read the book doubles each month.

1. Use this information to complete the table.

   number of months since January	number of people who have read the book
   0
   1
   2
   3
   4

2. What do you notice about the difference in the number of people who have read the book from month to month?
3. What do you notice about the factor by which the number of people changes each month?
4. At the beginning of a month, \(n\) people have read the book. How many people will have read the book at the beginning of the next month?

Solve each system of equations.

1. \(\begin{cases} x+y=2 \\ \text-3x-y=5 \\ \end{cases}\)

2. \(\begin{cases} \frac12x +2y = \text-13 \\ x-4y=8 \\ \end{cases}\)