The function

models the cost in dollars, c, of 1 ounce of a certain chemical used in a laboratory. x represents the number of years since 2010.

a. does the cost of the chemical increase or decrease over time, and by what percentage per year does it do so?

b. how much does an ounce of the chemical cost in 2018? Show your reasoning

a) increase by 4%

b) $ 98.54

Step-by-step explanation:

The given function is

We can rewrite this function as

Therefore the cost of the chemical increase over time by 4%

b) We want to find how much an ounce of the chemical cost in 2018.

Since 2010 to 2018, 8 years have passed.

We substitute x=8 to get:

(0,-3) see attached graph

step-by-step explanation:

a. to solve the system, graph the two equations.

x = y+3 becomes y=x-3 has m=1/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move up 1 unit and 1 unit to the right. plot a point and connect.

y=-4x+3 has m =-4/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move down four units and to the right 1 unit. plot a point and connect.

the solution is the point (x,y) where the two lines intersect. by the graph below it is (0,-3).

b. to solve by substitution, substitute y = -4x-3 into x= y+3

x= (-4x-3) +3

x=-4x

5x=0

x=0

now substitute x = 0 back in to find y.

y= -4(0)-3

y=0-3

y=-3

solution is (0,-3)

c. use elimination by adding the equations together.

x-y=3

4x+y=-3

5x=0

x=0

then substitute into one equation to find y.

y=-4(0)-3

y=-3

17

step-by-step explanation: