Selina Concise Class 7 Math Chapter 5 Exponents Exercise 5A Solution
EXERCISE 5A
(1) Find the value of:
(i) 62 = 6× 6 = 36
(ii) 73 = 7 × 7 × 7 = 343
(iii) 44 = 4 × 4 × 4 × 4 = 256
(iv) 55 = 5 × 5 × 5 × 5 × 5 = 3125
(v) 83 = 8 × 8 × 8 = 512
(vi) 75 = 7 × 7 × 7 × 7 × 7 = 16807
(2) Evaluate:
(i) 23 × 42
= 2 × 2 × 2 × 4 × 4
= 8 × 16
= 128
(ii) 23 × 52
= 2 × 2 × 2 × 5 × 5
= 8 × 25
= 200
(iii) 33 × 52
= 3 × 3 × 3 × 5 × 5
= 27 × 25
= 675
(iv) 22 × 33
= 2 × 2 × 3 × 3 × 3
= 4 × 27
= 108
(v) 32 × 53
= 3 × 3 × 5 × 5 × 5
= 9 × 125
= 1125
(vi) 53 × 24
= 5 × 5 × 5 × 2 × 2 × 2 × 2
= 125 × 16
= 2000
(vii) 32 × 42
= 3 × 3 × 4 × 4
= 9 × 16
= 144
(viii) (4 × 3)3
= (12)3
= 12 × 12 × 12
= 1728
(ix) (5 × 4)2
= (20)2
= 20 × 20
= 400
(3) Evaluate:
(4) Evaluate:
(5) Which is greater:
(i) 23 or 32
= (2 × 2 × 2) or (3 × 3)
= 8 < 9
(ii) 25 or 52
= (2 × 2 × 2 × 2 × 2) or (5 × 5)
= 32 > 25
(iii) 43 or 34
= (4 × 4 × 4) or (3 × 3 × 3 × 3)
= 64 < 81
(iv) 54 or 45
= (5 × 5 × 5 × 5) or (4 × 4 × 4 × 4 × 4)
= 625 < 1024
(6) Express each of the following in exponential form:
(i) 512 = 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 = 29
(ii) 1250 = 2 × 5 × 5 × 5 × 5 = 2 × 54
(iii) 1458 = 2 × 3 × 3 × 3 × 3 × 3 × 3 = 2 × 36
(iv) 3600 = 2 × 2 × 2 × 2 × 5 × 5 × 3 × 3 = 24 × 52 × 32
(v) 1350 = 2 × 3 × 3 × 3 × 5 × 5 = 2 × 33 × 52
(vi) 1176 = 2 × 2 × 2 × 3 × 7 × 7 = 23 × 3 × 72
(7) If a = 2 and b = 3, find the value of:
(i) (a + b)2 = (2 + 3)2 = 52 = 5 × 5 = 25
(ii) (b – a)3 = (3 – 2)3 = 13 = 1
(iii) (a × b)a = (2 × 3)2 = 62 = 6 × 6 = 36
(iv) (a × b)b = (2 × 3)3 = 63 = 6 × 6 × 6 = 216
(8) Express:
(i) 1024 = 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 = 210
(ii) 729 = 3 × 3 × 3 × 3 × 3 × 3 = 36
(iii) 343 = 7 × 7 × 7 = 73
(9) 27 × 32
= (3 × 3 × 3) × (2 × 2 × 2 × 2 × 2)
= 33 × 25
(10) 64 × 625
= (2 × 2 × 2 × 2 × 2 × 2) × (5 × 5 × 5 × 5)
= 26 × 54
(i) Value of a = 6 and b = 4
(ii) 2b × 5a
= 24 × 56
= (2 × 2 × 2 × 2) × (5 × 5 × 5 × 5 × 5 × 5)
= 16 × 1565
= 250000
thanks for helping me and write the numbers clean
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Question no. 10 is wrong the correct answer is 250000
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