Practice Test
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All the ordered pairs of an equation are points on its graph.
Use the graph to find the number of new vocabulary words y when the number of weeks x is 5.
Calculate the difference between the y-values when x=4 and x=6.
Interpretation: We learn 15 new vocabulary words every week.
75 new vocabulary words
30 more vocabulary words
| x | y=15x | y | (x,y) |
|---|---|---|---|
| 1 | y=15( 1) | 15 | ( 1, 15) |
| 2 | y=15( 2) | 30 | ( 2, 30) |
| 3 | y=15( 3) | 45 | ( 3, 45) |
All the ordered pairs of the equation are points on its graph. Let's plot the points (1,15), (2,30), and (3,45) and draw a straight line between them to get our graph.
Next, we want to interpret the slope. Let's look at the graph and find out how y changes for every step x increases by 1.
We can see that y increases by 15 when x increases by 1. In our context, this means that we learn 15 new vocabulary words every week.
y=15 x ⇓ y=15( 5)=75 Another way to solve the exercise is to use the graph of the equation we made in Part A. Let's use it to check our answer!
We can see that our answer is correct. We learn 75 new vocabulary words after 5 weeks.
Let's evaluate the value of y when x is 4 and 6. y=15( 4)= 60 y=15( 6)= 90 Now, we can calculate the difference between the two values of the number of words y. 90- 60=30 This means that we learn 30 more vocabulary words after 6 weeks than after 4 weeks.