Скачать или смотреть Ex 1.5 class 9 Number Systems [Important Exercise]

Ex 1.5 class 9 [Important Exercise]
Number Systems

1. Classify the following numbers as rational or irrational: [0:08]
(i) 2-√5
(ii) (2-√23)-√23
(iii) 2√7 / 7√7
(iv) 1/√2
(v) 2√23
(vi) 2π

2. Simplify each of the following expressions: [3:33]
(i) (3+√3) (2+√2)
(ii) (3+√3) (3-√3)
(iii) (√5 +√2)^2
(iv) (5-√2) (5+√2)

3. Recall π, is defined as the ratio of the circumference (say c) of a circle to its diameter (say d). That is, π (pi)= c/d. This seems to contradict the fact that π is irrational. How will you resolve this contradiction? [12:45]

4. Represent 9.3 on the number line. [18:31]

5. Rationalize the denominators of the following: [14:19]
(i) 1/√7
(ii) 1/(√7-√6)
(iii) 1/(√5+√2)
(iv) 1/(√7-2)

Note it down :
(i) The sum or difference of a rational number and an irrational number is irrational
(ii) The product or quotient of a non-zero rational number with an irrational number is irrational
(iii) If we add, subtract, multiply or divide two irrationals, the result may be rational or irrational

Understand the concept:
(i) "Simplify the expression" means expression should be written as the sum of a rational and an irrational number
(ii) When the denominator of an expression contains a term with a square root, the process of converting it to an equivalent expression whose denominator is a rational number is called "rationalizing the denominator"

Do watch:
   • Number System- Class 9th  


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