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Roots and powers Chapter 4.

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Presentation on theme: "Roots and powers Chapter 4."— Presentation transcript:

1 Roots and powers Chapter 4

2 4.1 – Estimating roots Chapter 4

3 radicals Estimate each radical, and then check the real answer on your calculator. Consider whether each value is exact or an approximate.

4 Pg. 206, #1–6 Independent Practice

5 4.2 – irrational numbers Chapter 4

6 Rational and irrational numbers

7 Irrational numbers An irrational number cannot be written in the form m/n, where m and n are integers and n ≠ 0. The decimal representation of an irrational number neither terminates nor repeats. When an irrational number is written as a radical, the radical is the exact value of the irrational number. approximate values exact value

8 example Tell whether each number is rational or irrational. Explain how you know. a) b) c) –3/5 is rational, because it’s written as a fraction.  In its decimal form it’s –0.6, which terminates. b) is irrational since 14 is not a perfect square. The decimal form is … which neither repeats nor terminates. c) is rational because both 8 and are perfect cubes. Its decimal form is … which is a repeating decimal.

9 The number system Together, the rational numbers and irrational numbers for the set of real numbers. Real numbers Rational numbers Integers Irrational numbers Whole numbers Natural Numbers

10 example Use a number line to order these numbers from least to greatest.

11 Pg , #4, 7, 8, 12, 15, 18, 2o Independent Practice

12 4.3 – Mixed and entire radicals
Chapter 4

13 Mixed and entire radicals
Draw the following triangles on the graph paper that has been distributed, and label the sides of the hypotenuses. 1 cm 4 cm 1 cm 3 cm 3 cm 2 cm 4 cm Draw a 5 by 5 triangle. What are the two ways to write the length of the hypotenuse? 2 cm

Why? We can split a square root into its factors. The same rule applies to cube roots. Why?

15 Multiplication properties of radicals
where n is a natural number, and a and b are real numbers. We can use this rule to simplify radicals:

16 example Simplify each radical. a) b) c)

17 example Write each radical in simplest form, if possible. a) b) c)
Try simplifying these three:

18 example Write each mixed radical as an entire radical. a) b) c)
Try it:

19 P , #4, 5, 10 and 11(a,c,e,g,i), 14, 19, 24 Independent practice

20 4.4 – fractional exponents and radicals
Chapter 4

21 Fill out the chart using your calculator.
Fractional exponents Fill out the chart using your calculator. What do you think it means when a power has an exponent of ½? What do you think it means when a power has an exponent of 1/3? Recall the exponent law: When n is a natural number and x is a rational number:

22 example Evaluate each power without using a calculator. a) b) c) d)
Try it:

23 Powers with rational exponents
When m and n are natural numbers, and x is a rational number, Write in radical form in 2 ways. Write and in exponent form.

24 example Evaluate: a) b) c) d)

25 example Biologists use the formula b = 0.01m2/3 to estimate the brain mass, b kilograms, of a mammal with body mass m kilograms. Estimate the brain mass of each animal. A husky with a body mass of 27 kg. A polar bear with a body mass of 200 kg.

26 Pg , #3, 5, 10, 11, 12, 17, 20. Independent practice

27 4.5 – negative exponents and reciprocals
Chapter 4

28 challenge Factor: 5x2 + 41x – 36

29 Hint: try using fractions.
consider This rectangle has an area of 1 square foot. List 5 possible pairs of lengths and widths for this rectangle. (Remember, they will need to have a product of 1). Hint: try using fractions.

30 What is the rule for any number to the power of 0? Ex: 70?
reciprocals Two numbers with a product of 1 are reciprocals. So, what is the reciprocal of ? So, 4 and ¼ are reciprocals! What is the rule for any number to the power of 0? Ex: 70? If we have two powers with the same base, and their exponents add up to 0, then they must be reciprocals. Ex: 73 ・ 7-3 = 70

31 So, 73 and 7-3 are reciprocals.
73 ・ 7-3 = 70 So, 73 and 7-3 are reciprocals. What is the reciprocal of 343? 73 = 343 When x is any non-zero number and n is a rational number, x-n is the reciprocal of xn. That is,

32 example Evaluate each power. a) b) c) Try it:

33 example Evaluate each power without using a calculator. a) b) Recall:
Try it (without a calculator):

34 example Paleontologists use measurements from fossilized dinosaur tracks and the formula to estimate the speed at which the dinosaur travelled. In the formula, v is the speed in metres per second, s is the distance between successive footprints of the same foot, and f is the foot length in metres. Use the measurements in the diagram to estimate the speed of the dinosaur.

35 Pg , #3, 6, 7, 9, 13, 14, 16, 21 Independent Practice

36 4.6 – applying the exponent laws
Chapter 4

37 Exponent laws review Recall:

38 Try it Find the value of this expression where a = –3 and b = 2.

39 example Simplify by writing as a single power. a) b) c) d) Try these:

40 example Simplify. a) b) Try this:

41 challenge Simplify. There should be no negative exponents in your answer:

42 example Simplify. a) b) c) d) Try these:

43 example A sphere has volume 425 m3.
What is the radius of the sphere to the nearest tenth of a metre?

44 Pg , #9, 10, 11, 12, 16, 19, 21, 22 Independent Practice

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