(a) The equation of the line, written in point-slope form is:
Step 1: Find the slope.
=
= -3/2.
Step 2: Use point (4,15) and slope (m) from step 1 and complete the equation in point-slope form.
y - 15 = -3/2(x - 4)
(b) Step 1: At 0 days, Amy's sales time was 21 minutes.
Step 2: Amy’s sales time decreased 3/2 minutes per day.
(c) The equation in slope-intercept form is y = -3/2(x) + 21.
In Mathematics and Geometry, the point-slope form of a straight line can be calculated by using the following mathematical equation (formula):
![y - y_1 = m(x - x_1)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/114ibzuj57ml08mu59z59vjg3t4kik0hxk.png)
Where:
- x and y represent the data points.
- m represent the slope.
Part a.
Step 1: First of all, we would determine the slope of this line by using these points (4, 15) and (8, 9);
Slope (m) = (9 - 15)/(8 - 4)
Slope (m) = -6/4
Slope (m) = -3/2
Step 2.
At data point (4, 15) and a slope of -3/2, an equation for this line can be calculated by using the point-slope form as follows:
y - 15 = -3/2(x - 4)
Part b.
Based on the model, Amy's sales time was 21 minutes at 0 days. Hence, it initially took Amy 21 minutes to sell a cupcake. Also, Amy’s sales time decreased 3/2 minutes per day.
Part c.
Next, we would rewrite the equation Part (a) from point-slope form to slope-intercept form as follows;
y - 15 = -3/2(x - 4)
y = -3/2(x) + 6 + 15
y = -3/2(x) + 21
Complete Question:
Amy sells cupcakes. The graph shows a linear model for her sales times in minutes on different days.
(a) What is the equation of the line, written in point-slope form? Show your work.
Step 1: Find the slope.
= _____- ____ = ______
Step 2: Use point (4,15) and slope (m) from step 1 and complete the equation in point-slope form.
y - _____ = _____ (x - ______)
(b) Based on the model, how long did it initially take Amy to sell a cupcake? Approximately how much did her sales time decreased each day?
Step 1: At 0 days, what was her sales time? _________ minutes
Step 2: Amy’s sales time decreased ________ minutes per day
(c) Bonus: Rewrite the equation Part (a) from point-slope form to slope-intercept form.