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Brilliant’s Composite Mathematics Class 8 Solutions Chapter 2 Cubes and Cube Roots
Welcome to NCTB Solutions. Here with this post we are going to help 8th class students for the Solutions of Brilliant’s Composite Mathematics Class 8 Book Solution, Chapter 2, Cubes and Cube Roots. Here students can easily find step by step solutions of all the problems for Cubes and Cube Roots, Exercise 2.1 and 2.2 Also here our mathematics teacher’s are solved all the problems with easily understandable methods with proper guidance so that all the students can understand easily.
Cubes and Cube Roots Exercise 2.1 Solution
Question no – (2)
Solution :
(i) 128
∴ 128 is not a perfect cube.
(ii) 3375
∴ 3375 is a perfect cube.
(iii) 1331
∴ 1331 is a perfect cube.
(iv) 27000
∴ 27000 is a perfect cube.
(v) 1000
∴ 1000 is a perfect cube.
Question no – (3)
Solution :
∴ 5 multiple of 3 are 3, 6, 9 18, 27.
∴ 27 is a such a number which is a cube of a number and multiple of 27.
Question no – (4)
Solution :
∴ 675 has to multiply with 5
To get a perfect cube.
(b) 675 has to be divided by 25 to get a perfect cube.
Question no – (5)
Solution :
5400 = 2 × 2 × 2 × 3 × 3 × 3 × 5 × 5
∴ 5 is the last number by which 5400 has to be multiplied to get a perfect cube.
Question no – (6)
Solution :
Volume = 13 × 13 × 13
= 2197 m3
Question no – (8)
Solution :
∴ We have to multiply 7 × 13 × 13
= 1183
∴ The cube root will be = 2 × 3 × 7 × 13
= 546
Question no – (9)
Solution :
Length of side = 3√125
= 125 ÷ 5 = 25
= 25 ÷ 5 = 5
= 5 m.
Therefore, the length of a side of the cube will be 5 m.
Question no – (10)
Solution :
(i) 3√ 8 × 125
= 3√ 8 × 125
= 3√2 × 2 × 2 × 5 × 5 × 5
= 2 × 5
= 10
(ii) 3√64 × – 729
= – 3√2 × 2 × 2 × 2 × 2 × 2 × 3 × 3 × 3 × 3 × 3 × 3
= – 2 × 2 × 3× 3
= – 36
(vii) 3√-27/1000
= – 3√3 × 3 × 3 /2 × 2 × 2 × 5 × 5 × 5
= – 3/ 2 × 5
= – 3/10
Question no – (11)
Solution :
Length of the box = 3√32.768m
= 3√32768/1000 m
= 2 × 2 × 2 × 2 × 2/10
= 3.2
For more better understanding purpose :
Cubes and Cube Roots Exercise 2.2 Solution
Question no – (1)
Solution :
Given, 732.
= 3√732
= 3√12 × 61
= 3√12 × 3√61
= 2.289 × 3.936
= 9.009
Question no – (6)
Solution :
Given, 31/216
= 3√31/216
= 3√31/3√216
= 3.141/6
= 0.524
Question no – (8)
Solution :
Given, -950.
= 3√- 950
= – 3√950
= – (3√95 × 3√10)
= – (4.563 × 2.154)
= – 9.830
Question no – (13)
Solution :
Given, -2 10/27.
= 3√- 2 10/27
= – 3√64/27
= – 3√64/3√27
= – 4/3
= – 1.3
Question no – (16)
Solution :
∴ Side = 3√450
= 3√45 × 3√10
= 3.557 × 2.154
= 7.67
Therefore, the length of its side will be 7.67
Previous Chapter Solution :
