Commutative and Associative Properties
Examples and Exercises
Answers
Solution to Example 7.6
| ⓐ | |
| \((3+0.6)+0.4=\)______ | |
| Change the grouping. |
\((3+0.6)+0.4=3+(0.6+0.4)\) |
Notice that $$0.6+0.4$$ is $$1$$, so the addition will be easier if we group as shown on the right.
| ⓑ | |
| \(\left(-4 \cdot \frac{2}{5}\right) \cdot 15=\) _______ | |
| Change the grouping. | \(\left(-4 \cdot \frac{2}{5}\right) \cdot 15=-4 \cdot\left(\frac{2}{5} \cdot 15\right)\) |
Notice that \(\frac{2}{5}⋅15\) is \(6\). The multiplication will be easier if we group as shown on the right.
Try It 7.11
(a) \((1+0.7)+0.3=1+(0.7+0.3)\)
(b) \((-9 \cdot 8) \cdot \frac{3}{4}=-9\left(8 \cdot \frac{3}{4}\right)\)
Try It 7.12
(a) \((4+0.6)+0.4=4+(0.6+0.4)\)
(b) \((-2 \cdot 12) \cdot \frac{5}{6}=-2\left(12 \cdot \frac{5}{6}\right)\)