1718 WB1Y CH6+9 Lesson 6

• Wiskunde
• Middelbare school
• vwo
• Leerjaar 1

Which exercises should we discuss on the board?

Writing formulas shorter

The formula 24 - 3 x time = height can be shortened.

When you write a formula shorter you do two things:
- replace the variable with a letter that represents that variable
- leave out the multiplication sign.

Writing formulas shorter

24 - 3 x time = height
- replace the variable with a letter that represents that variable.
24 - 3 x t = h
- leave out the multiplication sign.
24 - 3t = h

Mistakes to watch out for!

- replace the variable with a letter that represents that variable
12 + 3 x time = temperature
12 + 3 x t = t  is WRONG, because you use the letter t for two different variables. Possible ways to shorten the formula are:
12 + 3 x t = T
12 + 3 x t = c                (c for temperature in degrees Celcius)
12 + 3 x h = c               (h for time in hours)
etc.

Mistakes to watch out for!

- replace the variable with a letter that represents that variable
50 - 4 x time = water level
50 - 4 x t = w l  is WRONG, because you use two letters for one variable (water level).
Only use one letter per variable:
50 - 4 x t = w

Mistakes to watch out for!

- leave out the multiplication sign.
12 - a x 3 = t
12 - a3 = t is WRONG! When leaving out the multiplication sign in a x 3, you always write the number before the letter. a x 3 = 3 x a = 3a.

You shorten the formula like this:
12 - 3a = t

Shorten the formula
12 + 3 x time = height

Shorten the formula
price = 50 + time x 10

Shorten the formula
b = a x 15 -2

Shorten the formula
number of yellow beads = number of blue beads x 5

Homework Monday

§9.1: make and correct 1, 2, 3, 4, 5, 6