Ayushree
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Which of the following is the greatest? Explain your reasoning. (i) 67³ – 66³ (ii) 43³ – 42³ (iii) 67² – 66² (iv) 43² – 42²

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Use identity:
a³ – b³ = (a–b)(a² + ab + b²),
a² – b² = (a–b)(a + b).
(i) has largest numbers and cube difference. So, 67³ – 66³ is the greatest.

Class 8 Mathematics Ganita Prakash A Square and A Cube

Class 8 Mathematics Ganita Prakash Chapter 1 A Square and A Cube NCERT solutions

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1 Answer

  1. Let’s compare using identities:
    a³ – b³ = (a–b)(a² + ab + b²)
    67³ – 66³ = 1(4489 + 4422 + 4356) = 13267
    43³ – 42³ = 1(1849 + 1806 + 1764) = 5419
    a² – b² = (a–b)(a + b)
    67² – 66² = 1(133) = 133
    43² – 42² = 1(85) = 85
    So, the greatest is 67³ – 66³

     

    For more NCERT Solutions for Class 8 Mathematics Ganita Prakash Chapter 1 A Square and A Cube Extra Questions & Answer:

    https://www.tiwariacademy.com/ncert-solutions/class-8/maths/ganita-prakash-chapter-1/

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