#1
27th March 2016, 02:22 PM
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Mixed Surd Examples
Sir I am teaching surds to the students but I have some problems in the mixed surd so can you tell me that what is the mixed surd and the example
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#2
27th March 2016, 02:23 PM
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Re: Mixed Surd Examples
Hey buddy a surd is an irrational number, a number which cannot be expressed as a fraction or as a terminating or recurring decimal. It is left as a square root. It can also be a non-cube number left in cube root form and so on. Number. Decimal. Mixed Surd: Surds such as 2√3, 3√9 are called mixed surds as they containrational numbers such as 2, 3 and surds such as √3 and √9 I. A mixed surd can be expressed in the form of a pure surd. For example, (i) 3√5 = 32⋅5−−−−√ = 9⋅5−−−√ = √45 (ii) 4 ∙ ∛3 = 43−−√3 ∙ ∛3 = 64−−√3 ∙ ∛3 = 64−−√3⋅3 = ∛192 In general, x y√n = xn−−√n ∙ y√n = xny−−−√n II. Sometimes a given pure surd can be expressed in the form of a mixed surd. For example, (i) √375 = 53⋅3−−−−√ = 5√15; (ii) ∛81 = 34−−√3 = 3∛3 (iii) ∜64 = 26−−√4 = 222−−√4= 24√4 But ∛20 can't be expressed in the form of mixed surd. What is a Surd? A surd is an irrational number. We know √4 = 2, √9 = 3, √16 = 4, But what is √2 =? and √5 =? √2 and √5 are not rational numbers such as √4, √9 and √16 and others which are all rational numbers. Rational numbers include terminating and non-terminating decimals. ½ is a terminating decimal, 0.5 and 1/3 is a non-terminating decimal, 0.3333…. But √2 = 1.414215…….. can be expressed as neither a terminating nor a non-terminating decimal. So, √2 is a surd. Examples of Surds: 2√2 or just √2 is a surd. 3√9, 3√16, 4√25, 5√100 are all numbers whose given roots are not rational numbers. They are therefore Surds. Note: 2√8 or just √8 is irrational and therefore a Surd, but 3√8 = 2, a rational number, so, 3√8 is not a surd. What is Not a Surd? In the surd n√a, a is a rational number. In n√a, if a is irrational, then n√a is not called a Surd. From this definition: √8 is a surd as 8 is a rational number and √8 is irrational, but √ (2 + √3) is not a surd as (2 + √3) is not a rational number, and also 2√ (2√81) = 2√9 = 3, a rational number. Therefore, 2√ (2√81) is not a surd. Note: Every surd is irrational, but every irrational number is not a surd. Order of a Surd: In the surd n√a, n is called order of the surd. Examples: 2√3 is a surd of order 2 4√12 is a surd of order 4, 100√3 is a surd of order 100. Note: If the order of surd is 2, it is optionally dropped. 2√3 is same as √3. Types of Surds: The following are various types of Surds: Pure Surd: Surds such as √3, 3√9 which are entirely irrational numbers are called pure surds Compound Surd: Surds such as √2 + √3, √3 - √2 are called Compound Surds. Compound surds are sum or difference of two other surds. Like Surds or Similar Surds: Surds that are different multiples of same surds are called similar surds. Example: √80 and √45, because √80 = √ (5 × 16) = 4√5 and √45 = √ (5 × 9) = 3 √5 Conjugate Surds: Two surds of the form x + √y and x - √y are called conjugate surds. Example: 2 + √3 and 2 - √3 are called conjugate surds. Note: The sum or difference of two conjugate surds is a rational number. (2 + √3) + (2 - √3) = 4, a rational number. |