a) 430 b)
Explanation:
The initial area = 490 square foot
Each day, we have a decrease of 60 square foot of painting
for the 1st day:
The amount remaining = 490 - 60 = 430 square ft
for 2nd day:
The amount remaining = 430 - 60 = 370 square ft
The equaton:
The amount remaining = 490 - 60(d)
were d = number of days
3rd day: d = 3
The amount remaining = 490 - 60(3) = 310 square ft
4th day: d = 4
The amount remaining = 490 - 60(4) = 250 square ft
5th day: d = 5
The amount remaining = 490 - 60(5) = 190 square ft
To determine the decay, we can find the change in area:
[tex]\begin{gathered} \text{let use points (d, A)}\colon\text{ (1, 490) and (2, 430)} \\ \text{slope = }\frac{490-\text{ 430}}{2-1}\text{ = 60/1 = 60} \\ \\ \text{points (d, A)}\colon\text{ (2, 430) and (3, 370)} \\ \text{slope = }\frac{430-370}{3-2}\text{ = 60/1 = 60} \end{gathered}[/tex]
The rate of change is constant. It is a linear decay as the graph of th points will show a straight line with negative slope
