1718 WB1Y CH6+9 Lesson 5

• Wiskunde
• Middelbare school
• vwo
• Leerjaar 1

Which exercises should we discuss on the board?

Graph --> Table --> Formula

How to make a formula from a linear graph

1) Make a table for the graph (horizontal axis = top row, vertical axis = bottom row), fill in values you can read off exactly (grid points)

Graph --> Table --> Formula

2) Read off the start value from the table
You can find the start value in the bottom row (vertical axis) when the value in the the top row (horizontal axis) is 0.

start  value = 4

Graph --> Table --> Formula

3) Calculate the gradient (how much does the graph rise or fall per horizontal step)
You can calculate the gradient by finding how much the bottom row (vertical axis) increases and dividing this by how much the top row (horizontal axis) increases.

gradient = 0.8

Graph --> Table --> Formula

4) Fill in the formula
All linear formulas have the form:
[Start Value] +/- [Gradient] x [Horizontal Variable] = [Vertical Variable]

start value = 4, gradient = 0.8,
horizontal axis = distance, vertical axis = height
graph is rising, so +

Formula: 4 + 0.8 x distance = height

Formulas

Sometimes formulas are written in a different order.  They all give the same result, because they follow the order of operations.

4 + 0.8 x distance = height
4 + distance x 0.8 = height
0.8 x distance + 4 = height
height = distance x 0.8 + 4
etc.

Homework Friday

- Make and correct: §6.5: 28, 29, 30, 32, 33 (so not 31)
- Bring book 1B (or download it)
- Don't forget it is "Purple Friday"