Math Problem Statement

Answer the following questions: 1. Find the cube root of 6859. 2. Find the cube root of 13824 through estimation. 3. Find the smallest number by which 3087 must be divided so that the quotient is a perfect cube. 4. Is 392 a perfect cube? 5. By what least number should 968 be multiplied to get a perfect cube number? Find the number whose cube is the new number. 6. Is the cube of 4913 an odd number? Why? 7. Is the cube of 132651 an even number? Why? 8. Find the cubes of the numbers 4, 8, 15, 0.2, 1.1. 9. Find the cube roots of 4 - 12/125, -0.729, 5832, 64000, 10648.

Solution

Let’s go through each of the questions and solve them one by one:

1. Find the cube root of 6859.

To find the cube root of 6859:

68593=19\sqrt[3]{6859} = 19

2. Find the cube root of 13824 through estimation.

Since 203=800020^3 = 8000 and 303=2700030^3 = 27000, the cube root of 13824 lies between 20 and 30. You can estimate that it is around 24.

138243=24\sqrt[3]{13824} = 24

3. Find the smallest number by which 3087 must be divided so that the quotient is a perfect cube.

First, factorize 3087: 3087=33×193087 = 3^3 \times 19 To make it a perfect cube, divide by 19, leaving 333^3, which is a perfect cube.

4. Is 392 a perfect cube?

Factorizing 392: 392=23×7392 = 2^3 \times 7 Since all factors are not perfect cubes, 392 is not a perfect cube.

5. By what least number should 968 be multiplied to get a perfect cube? Find the number whose cube is the new number.

Factorize 968: 968=23×11968 = 2^3 \times 11 To make it a perfect cube, multiply by 11211^2. The number becomes 23×113=(2×11)3=2232^3 \times 11^3 = (2 \times 11)^3 = 22^3.

So, multiplying 968 by 112=12111^2 = 121, the new number is 223=1064822^3 = 10648.

6. Is the cube of 4913 an odd number? Why?

Since 4913 is an odd number, its cube will also be odd.

7. Is the cube of 132651 an even number? Why?

Since 132651 is an odd number, its cube will also be odd.

8. Find the cubes of these numbers:

  • 43=644^3 = 64
  • 83=5128^3 = 512
  • 153=337515^3 = 3375
  • 0.23=0.0080.2^3 = 0.008
  • 1.13=1.3311.1^3 = 1.331

9. Find the cube roots of these numbers:

(i) 4121254 - \frac{12}{125}
First simplify the expression 4121253.9044 - \frac{12}{125} \approx 3.904, and then: 3.90431.571\sqrt[3]{3.904} \approx 1.571

(ii) 0.7293=0.9\sqrt[3]{-0.729} = -0.9

(iii) 58323=18\sqrt[3]{5832} = 18

(iv) 640003=40\sqrt[3]{64000} = 40

(v) 106483=22\sqrt[3]{10648} = 22


Would you like further details on any of these solutions?

Here are 5 related questions to explore:

  1. What is the cube root of 15625?
  2. How do you check if a large number is a perfect cube?
  3. What is the smallest cube greater than 50000?
  4. How do you estimate cube roots using binomial expansion?
  5. What is the cube of 25.5?

Tip: Cube roots can often be estimated by checking the cubes of integers near the given number, especially for large numbers.

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Math Problem Analysis

Mathematical Concepts

Cube roots
Perfect cubes
Estimation
Factorization

Formulas

Cube root formula: ∛x
Cube of a number: x^3

Theorems

Properties of perfect cubes
Odd and even number properties in cubes

Suitable Grade Level

Grades 8-10