Selina Concise Class 7 Math Chapter 5 Exponents Exercise 5A Solution

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

Get next Exercise 5B solutions click here

7 Comments

Add a Comment
  1. thanks for helping me and write the numbers clean

    1. Question no. 10 is wrong the correct answer is 250000

  2. Helpful ..I found one Mistake

    1. Please share with us…

  3. Thanks for helping me

Leave a Reply

Your email address will not be published. Required fields are marked *