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history of mathematics - National STEM Centre

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outcome<br />

1 step to the right<br />

Figure 13.1<br />

162<br />

13 Hints<br />

1 step<br />

upwards'<br />

To stage the debate, or to draw up a plan for your presentation or essay, you could<br />

consider the following format:<br />

• first, summarise Arnauld's extract in Activity 10.10;<br />

• secondly, summarise Euler's and Saunderson's extracts.<br />

In each case you should draw out the key points. Then, you could start on the<br />

debate by<br />

• presenting what Arnauld is likely to believe is the flaw in Euler's and<br />

Saunderson's arguments;<br />

• allowing Euler and Saunderson to answer back or counterattack.<br />

Remember not to use modern arguments to present the flaws in the various<br />

arguments. Try to argue from the points <strong>of</strong> view <strong>of</strong> Arnauld, Euler and Saunderson<br />

based on what you know <strong>of</strong> them from the extracts. You could consult your list <strong>of</strong><br />

assumptions made by Euler and Saunderson; by looking at them can you find a<br />

'chink in their armour' from Arnauld's point <strong>of</strong> view, or vice versa?<br />

Activity 77.7, page 138<br />

1 How did you set about establishing the result for the product <strong>of</strong> two negative<br />

numbers? You should consider whether the process you used was a justifiable one<br />

given the original role <strong>of</strong> the numbers a, b, c and d.<br />

Activity 11.4, page 141<br />

1 One counter-example is the answer given to question Ic in Activity 10.10 in<br />

connection with Arnauld's opposition to negative numbers.<br />

Activity 11.8, page 143<br />

1 b The operations for combining the elements in Boole's algebra will not be<br />

labelled by + and x and the elements will not be labelled by numbers. Imagine<br />

replacing the symbols in the rules for combining Boole's elements by + and x in a<br />

suitable way and imagine the elements to be numbers. Would the rules then look the<br />

same as those for the number system? If not, how would they differ?<br />

Activity 11.10, page 145<br />

1 To get started, here is part b as an example; you can then try the other parts.<br />

Take a step <strong>of</strong> one unit to the right (i) and add to it a step <strong>of</strong> one unit 'upwards', (j).<br />

This produces a step as shown in Figure 13.1 but not in either <strong>of</strong> the basic directions<br />

(to the right and upwards); it is inclined at an angle to the basic directions.<br />

What is the angle at which this new step is inclined and what is its length?<br />

Activity 11.12, page 146<br />

2 b Think about something you take for granted with real numbers. When you<br />

multiply three numbers together can you multiply them in any order; does the order<br />

matter?

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