## RD Sharma Class 8 Solutions Chapter 4 Cubes and Cube Roots Ex 4.2

These Solutions are part of RD Sharma Class 8 Solutions. Here we have given RD Sharma Class 8 Solutions Chapter 4 Cubes and Cube Roots Ex 4.2

**Other Exercises**

- RD Sharma Class 8 Solutions Chapter 4 Cubes and Cube Roots Ex 4.1
- RD Sharma Class 8 Solutions Chapter 4 Cubes and Cube Roots Ex 4.2
- RD Sharma Class 8 Solutions Chapter 4 Cubes and Cube Roots Ex 4.3
- RD Sharma Class 8 Solutions Chapter 4 Cubes and Cube Roots Ex 4.4
- RD Sharma Class 8 Solutions Chapter 4 Cubes and Cube Roots Ex 4.5

**Question 1.
**

**Find the cubes of:**

**(i) -11**

**(ii) -12**

**(iii) – 21**

**Solution:**

(i) (-11)

^{3}=(-11)

^{3}=(11 x 11 x 11) =-1331

(ii) (-12)

^{3}=(-12)

^{3}=(12 x 12 x 12) = -1728

(iii) (-21)

^{3}=(-21)

^{3}=(21 x 21 x 21) = -9261

**Question 2.
**

**Which of the following numbers are cubes of negative integers.**

**(i) -64**

**(ii) -1056**

**(iii) -2197**

**(iv) -2744**

**(v) -42875**

**Solution:**

**∴ All factors of 64 can be grouped in triplets of the equal factors completely.**

∴ -64 is a perfect cube of negative integer.

All the factors of 1056 can be grouped in triplets of equal factors grouped completely

∴ 1058 is not a perfect cube of negative integer.

All the factors of -2197 can be grouped in triplets of equal factors completely

∴ 2197 is a perfect cube of negative integer,

All the factors of -2744 can be grouped in triplets of equal factors completely

∴ 2744 is a perfect cube of negative integer

All the factors of -42875 can be grouped in triplets of equal factors completely

∴ 42875 is a perfect cube of negative integer.

**Question 3.
**

**Show that the following integers are cubes of negative integers. Also, find the integer whose cube is the given integer :**

**(i) -5832 (ii) -2744000**

**Solution:**

Grouping the factors in triplets of equal factors, we see that no factor is left

∴ -5832 is a perfect cube

Now taking one factor from each triplet we find that

-5832 is a cube of – (2 x 3 x 3) = -18

∴ Cube root of-5832 = -18

Grouping the factors in tuplets of equal factors, we see that no factor is left. Therefore it is a perfect cube.

Now taking one factor from each triplet, we find that.

-2744000 is a cube of – (2 x 2 x 5 x 7) ie. -140

∴ Cube root of -2744000 = -140

**Question 4.
**

**Find the cube of :**

**Solution:**

**Question 5.
**

**Which of the following numbers are cubes of rational numbers :**

**Solution:**

Hope given RD Sharma Class 8 Solutions Chapter 4 Cubes and Cube Roots Ex 4.2 are helpful to complete your math homework.

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