Class 9 Maths
Number Systems
Ex.1.1 Q.1
Is zero a rational number?
Can you write it in the form where p and q are integers and q ≠ 0?
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Ex.1.1 Q.2
Find six rational numbers between 3 and 4.
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Ex.1.1 Q.3
Find five rational numbers between and
.
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Ex.1.1 Q.4
State whether the following statements are true or false. Give reasons for your answers.
(1) Every natural number is a whole number.
(2) Every integer is a whole number
(3) Every rational number is a whole number.
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Ex.1.2 Q.1
State whether the following statements are true or false. Justify your answers.
(1) Every irrational number is a real number.
(2) Every point on the number line is of the form √m where m is a natural number.
(3) Every real number is an irrational number.
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Ex.1.2 Q.2
Are the square roots of all positive integers irrational?
If not, give an example of the square root of a number that is a rational number.
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Ex.1.2 Q.3
Show how √5 can be represented on the number line.
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Ex.1.3 Q.1
Write the following in decimal form and say what kind of decimal expansion each has:
(1)
(2)
(3)
(4)
(5)
(6)
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Ex.1.3 Q.2
You know that = 0.
can you predict what the decimal expansion of
,
,
,
,
.
Are, without actually doing the long division? if so, how?
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Ex.1.3 Q.3
Express the following in the form where p and q are integers and q ≠ 0.
(1) 0.
(2) 0.4
(3) 0.
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Ex.1.3 Q.4
Express 0.99999 . . . in the form .
Are you surprised by your answer?
With your teacher and classmates discuss why the answer makes sense.
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Ex.1.3 Q.5
What can the maximum number of digits be in the repeating block of digits in the
decimal expansion of ? Perform the division to check your answer.
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Ex.1.3 Q.6
Look at several examples of rational numbers in the form (q ≠ 0),
where p and q are integers with no common factors other than 1
and having terminating decimal representations (expansions).
Can you guess what property q must satisfy?
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Ex.1.3 Q.7
Write three numbers whose decimal expansions are non-terminating non-recurring.
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Ex.1.3 Q.8
Find three different irrational numbers between the rational numbers and
.
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Ex.1.3 Q.9
Classify the following numbers as rational or irrational:
(1) √23
(2) √225
(3) 0.3796
(4) 7.478478…...
(5) 1.101001000100001...
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Ex.1.4 Q.1
Visualize 3.765 on the number line, using successive magnification.
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Ex.1.4 Q.2
Visualize 4. on the number line up to 4 decimal places.
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Ex.1.5 Q.1
Classify the following numbers as rational or irrational:
(1) 2 – √5
(2) (3 + √23) - √23
(3)
(4)
(5) 2π
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Ex.1.5 Q.2
Simplify each of the following expressions:
(1) (3 + √3) (2 + √2)
(2) (3 + √3) (3 - √3)
(3) (√5 + √2)2
(4) (√5 - √2) (√5 + √2)
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Ex.1.5 Q.3
Recall, π is defined as the ratio of the circumference (say c) of a circle to its diameter (say d).
That is, π = . This seems to contradict the fact that π is irrational.
How will you resolve this contradiction?
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Ex.1.5 Q.4
Represent √9.3 on the number line.
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Ex.1.5 Q.5
Rationalize the denominators of the following:
(1)
(2)
(3)
(4)
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Ex.1.6 Q.1
Find:
(1) 641/2
(2) 321/5
(3) 1251/3
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Ex.1.6 Q.2
Find:
(1) 93/2
(2) 322/5
(3) 163/4
(4) 125-1/3
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Ex.1.6 Q.3
Simplify:
(1) 22/3 × 21/5
(2) ( )7
(3)
(4) 71/2 × 81/2
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