Chapter 1) Real Numbers
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Extra Questions with solutions
Q1) Obtain HCF of 12056
and 420.
Q2) Show that any positive integer is of the form of 8q +1, 8q+3 or 8q+7, where q is some integer.
Q3) Show that cube of any positive integer is of the form of
9m, 9m+1 or 9m+8.
Q4) Use Euclid’s division algorithm to find HCF of 460 and 20468.
Q5) Show that n2
-1 is divisible by 8, if n is an odd positive integer.
Q6) Consider the numbers of the form 3n (where n is
a natural number). Check whether there is any value of n for which 3n ends with 2.
Q7) Find the HCF and LCM of 35 and 115 by prime
factorisation method.
Q8) Find HCF of 315
and 462 and hence find their LCM.
Q9) Find HCF and LCM of the following pairs of numbers:
a)
98 and
70:
b)
112
and 64:
Q10) There are 3 alarms A,
B, and C. A rings after every 3hrs, B
rings after every 4hrs and C rings
after every 6hrs. Find the time interval after which the 3 alarms ring together
after ringing once together.
Q11) Find the largest number that will divide 398, 436
and 542 leaving remainder 7,
11 and 15 respectively.
Q12) Which of the following rational numbers can be
represented as terminating decimals?
a) 3/5
b) 2/13
c) 7/20
Q13) Find HCF of 3675
and 43 using Euclid’s division
algorithm.
Q14) Using Euclid’s division lemma, prove that difference of
squares of 2 odd natural numbers is a multiple of 8.
Q15) Check whether 7n
can end with the digit ‘0’ for any
natural number n.
Q16) Given that HCF (189,144)
= 9, find their LCM.
Q17) If a is an
irrational number, them prove that -a
is also a irrational number.
Q18) Prove that 2 + 21/2 is not a rational number.
Q19) Without performing the long division process state
whether the following rational numbers will have terminating decimal expansion
or a non-terminating decimal expansion .
a)
17/8 b) 64/455 c) 29/343 d)15/1600 e)13/3125 f)23/2353
Q20) Prove that 51/2 + 31/2 is an irrational number.
Answers:
Q1) 4
Q4) 4
Q7) HCF = 5, LCM = 805
Q8) HCF = 21, LCM = 6930
Q9) a) HCF = 14, LCM = 490 b)HCF = 16, LCM = 448
Q10) 12hrs
Q11) 17
Q12) a) Terminating
b)Non-Terminating
c)Terminating
Q13) HCF = 21
Q15) no
Q16) 3024
Q19) a)Terminating
b)Non-Terminating
c)Non-Terminating
d)Terminating e)Terminating
f)Terminating
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handwritten_solution.pdf from the blog itself J
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