1. Work out: a) $(-4) + (-13)$
- When adding two negative numbers, add their absolute values and keep the negative sign.
$$-4 + (-13) = -(4 + 13) = -17$$
b) $(+8) + (-3) + (-2)$
- Add positive and negative numbers by combining positive and negative parts separately.
$$8 + (-3) + (-2) = 8 - 3 - 2 = 3$$
2. Solve the following using a number line: a) $2 - (+6)$
- Subtracting a positive number means moving left on the number line.
$$2 - 6 = -4$$
b) $(-4) - (-6)$
- Subtracting a negative number is the same as adding its positive.
$$-4 - (-6) = -4 + 6 = 2$$
3. Find the difference between Janet's and Elsie's arrival times.
- Janet was 8 minutes late (+8), Elsie was 5 minutes early (-5).
- Difference = $8 - (-5) = 8 + 5 = 13$ minutes.
4. Evaluate: a) $(-8) \times (-3) \times 4$
- Multiply stepwise, remembering that negative times negative is positive.
$$(-8) \times (-3) = 24$$
$$24 \times 4 = 96$$
b) $6 \times (-9)$
$$6 \times (-9) = -54$$
c) $(-5) \times (-2) \times (-5)$
$$(-5) \times (-2) = 10$$
$$10 \times (-5) = -50$$
5. Work out: a) $48 \div (-4)$
$$48 \div (-4) = -12$$
b) Rate of descent = total depth $\div$ time
$$\frac{-56}{8} = -7$$
- The diver descends at 7 metres per minute (negative indicates downward).
Final answers:
1a) $-17$
1b) $3$
2a) $-4$
2b) $2$
3) $13$ minutes
4a) $96$
4b) $-54$
4c) $-50$
5a) $-12$
5b) $-7$ metres per minute
Integer Operations E2617C
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