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Mixed and Entire Radicals. Expressing Entire Radicals as Mixed Radicals, and vice versa. Today’s Objectives. Students will be able to demonstrate an understanding of irrational numbers by: Expressing a radical as a mixed radical in simplest form (limited to numerical radicands)
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Mixed and Entire Radicals Expressing Entire Radicals as Mixed Radicals, and vice versa
Today’s Objectives • Students will be able to demonstrate an understanding of irrational numbers by: • Expressing a radical as a mixed radical in simplest form (limited to numerical radicands) • Expressing a mixed radical as an entire radical (limited to numerical radicands)
Proportions • Recall that we can name fractions in many different ways and they will be equivalent to each other, or proportional to each other • For example, all of the following fractions are equivalent to the fraction 3/12: 1/4 , 5/20 , 30/120 , 100/400 • Why is ¼ the simplest form of 3/12?
Equivalent expressions • Just as with fractions, equivalent expressions for any number have the same value • Example: • √16*9 is equivalent to √16 * √9 because, • √16*9 = √144 = 12 and √16 * √9 = 4*3 = 12 • Similarly, 3√8*27 is equivalent to 3√8 * 3√27 because, • 3√8*27 = 3√216 = 6 and 3√8 * 3√27 = 2*3 = 6 • Multiplication Property of Radicals • n√ab = n√a * n√b, where n is a natural number, and a and b are real numbers
Multiplication Property • We can use this property to simplify square roots and cube roots that are not perfect squares or perfect cubes • We can find their factors that are perfect squares or perfect cubes • Example: the factors of 24 are: 1,2,3,4,6,8,12,24 • We can simplify √24 because 24 has a perfect square factor of 4. • Rewrite 24 as the product of two factors, one being 4 • √24 = √4*6 = √4*√6 = 2*√6 = 2√6 • We can read 2√6 as “2 root 6”.
Multiplication Property • Similarly, we can simplify 3√24 because 24 has a perfect cube factor of 8. • Rewrite 24 as the product of two factors, one being 8 • 3√24 = 3√8*3 = 3√8 *3√3 = 23√3 • We can read this as “2 cube root 3”. • However, we cannot simplify 4√24 because 24 has no factors that can be written as a 4th power • We can also use prime factorization to simplify a radical
Example 1) Simplifying Radicals Using Prime Factorization • Simplify the radical √80 • Solution: • √80 = √8*10 = √2*2*2*5*2 • = √(2*2)*(2*2)*5 = √4*√4*√5 • =2*2*√5 • 4√5 • Your turn: • Simplify the radical 3√144 • Simplify the radical 4√162 • = 23√18, 34√2
Multiple Answers • Some numbers, such as 200, have more than one perfect square factor • The factors of 200 are: 1,2,4,5,8,10,20,25,40,50,100,200 • Since 4, 25, and 100 are perfect squares, we can simplify √200 in three ways: • 2√50, 5√8, 10√2 • 10√2 is in simplest form because the radical contains no perfect square factors other than 1. • So, to write a radical of index n in simplest form, we write the radicand as a product of 2 factors, one of which is the greatest perfect nth power
Example 2) Writing Radicals in Simplest Form • Write the radical in simplest form, if possible. • 3√40 • Solution: • Look for the perfect nth factors, where n is the index of the radical. • The factors of 40 are: 1,2,4,5,8,10,20,40 • The greatest perfect cube is 8 = 2*2*2, so write 40 as 8*5. • 3√40 = 3√8*5 = 3√8*3√5 = • 23√5 • Your turn: • Write the radical in simplest form, if possible. • √26, 4√32 • Cannot be simplified, 24√2
Mixed and Entire Radicals • Radicals of the form n√x such as √80, or 3√144 are entire radicals • Radicals of the form an√x such as 4√5, or 23√18 are mixed radicals • We already rewrote entire radicals as mixed radicals in Examples 1 and 2 • Here is one more example going the opposite way (mixed radical entire radical)
Example 3) Writing Mixed Radicals as Entire Radicals • Write the mixed radical as an entire radical • 33√2 • Solution: • Write 3 as: 3√3*3*3 = 3√27 • 33√2 = 3√27 * 3√2 = 3√27*2 = • 3√54 • Your turn: • Write each mixed radical as an entire radical. • 4√3, 25√2 • √48, 5√64
Review • Multiplication Property of Radicals is: • n√ab = n√a * n√b, where n is a natural number, and a and b are real numbers • to write a radical of index n in simplest form, we write the radicand as a product of 2 factors, one of which is the greatest perfect nth power • Radicals of the form n√x such as √80, or 3√144 are entire radicals • Radicals of the form an√x such as 4√5, or 23√18 are mixed radicals
Homework • Pg. 218 - 219 • (4-5)aceg, 7a, 9, 11acegi, 14,17,19, 21, 24