Answers

14

a) \(\operatorname{LCM}(65,70)=910\) seconds \(=15\) minutes \(10\) seconds.
b) \(\dfrac{910}{65}=14\) laps.

15

\(554\) is divisible by 2.

16

a) \(141\) — No, \(141=3\times47\)
b) \(163\) — Yes
c) \(121\) — No, \(121=11^2\)
d) \(191\) — Yes
e) \(119\) — No, \(119=7\times17\)

17

a) \(5^2=25\)
b) \(\sqrt{36}=6\)
c) \(10^2=100\)
d) \(\sqrt{169}=13\)
e) \(\sqrt1=1\)
f) \(11^2=121\)

18

\[ \text{Side length}=\sqrt{144}=12\text{ cm} \]

19

a) \(3^3=27\)
b) \(\sqrt[3]{8}=2\)
c) \(\sqrt[3]{125}=5\)
d) \(\sqrt[3]{27}=3\)

20

a) \(\sqrt{25}\times\sqrt[3]{64}=5\times4=\boxed{20}\)
b) \(\sqrt{144}-\sqrt[3]{27}=12-3=\boxed{9}\)

Animals and plants in the desert have special adaptations that help them survive in a hot and dry environment. Cacti and other desert plants store water in their thick stems and have long roots to collect water from the soil. Their spines protect them from animals and help reduce water loss. Many desert animals, such as camels, foxes, and snakes, rest in shade or underground during the hottest part of the day. Some animals come out at night when it is cooler. In this way, desert animals and plants can live with very little water.

Desert plants and animals have special ways to survive. Cacti store water, while animals such as camels and snakes avoid the heat by resting in the shade or coming out at night. They can live with very little water.