This lesson contains 14 slides, with interactive quizzes and text slides.
Lesson duration is: 50 min
Items in this lesson
Which exercises should I discuss on the board?
Slide 1 - Mind map
Recap: Writing formulas shorter
- Replace the variables with one letter for each variable - Remove the multiplication sign (x), always write the number before the letter. 15 - 3 x time = height can be written shorter as 15 - 3t = h
Slide 2 - Slide
Write the formula as short as possible price = 3 + 1.5 x number of chocolates
Slide 3 - Open question
Write the formula as short as possible 24 - time x 4 = height
Slide 4 - Open question
More writing formulas shorter
In formulas that contain brackets can be written shorter too, by removing the multiplication sign. p = 10 + 2 x (t - 5) can be written shorter as p = 10 + 2(t - 5)
a = 2.5 x (d + 2) + 4 can be written shorter as a = 2.5(d+2) + 4
Slide 5 - Slide
Write the formula as short as possible r = 3 + 2 x (q - 4)
Slide 6 - Open question
Working with (shortened) formulas
When using a shortened formula, remember that there is an "invisible" multiplication sign!
h = 19 - 2t corresponds to a candle. Here h is the height of a candle in cm and t is the time in hours. Calculate the height of the candle after 6 hours.
Slide 7 - Slide
Working with (shortened) formulas
When using a shortened formula, remember that there is an "invisible" multiplication sign! h = 19 - 2t corresponds to a candle. Here h is the height of a candle in cm and t is the time in hours. Calculate the height of the candle after 6 hours.
6 hours corresponds to t = 6. Replace t with the number 6 in the formula and add the "invisible" multiplication sign. Calculate following the order of operations.
h = 19 - 2 x 6 = 19 - 12 = 7
The height of the candle after 6 hours is 7 cm.
Slide 8 - Slide
Working with (shortened) formulas
The formula q = 12 - 5(t + 2) is given. Calculate q when t = 4.
Replace t with 4 and add the "invisible" multiplication sign. Calculate following the order of operations.
q = 12 - 5x(4 + 2)= 12 - 5 x 6 = 12 - 30 = -18
When t = 4, q = -18
Slide 9 - Slide
Calculate a when c = 3 a = 5c - 2
A
51
B
6
C
13
D
9
Slide 10 - Quiz
Calculate y when t = -2 y = 10 + 3t
A
16
B
4
C
11
D
-26
Slide 11 - Quiz
Calculate h when t = 6 h = 5 + 3(t - 1)
A
20
B
40
C
13
D
something else
Slide 12 - Quiz
Calculate p when n = -3 p = 20 - 5(n+1)
A
40
B
10
C
0
D
something else
Slide 13 - Quiz
Homework Tuesday
§9.2, make and correct: 7, 8, 9, 10, 11, 12, 13, 15 (so not 14)