Home
Class 12
MATHS
If n is an odd integer greater than or e...

If n is an odd integer greater than or equal to 1, then the value of `n^3 - (n-1)^3 + (n-1)^3 - (n-1)^3 + .... + (-1)^(n-1) 1^3`

A

`((n+1)^(2)(2n-1))/(4)`

B

`((n-1)^(2)(2n-1))/(4)`

C

`((n+1)^(2)(2n+1))/(4)`

D

None of these

Text Solution

AI Generated Solution

The correct Answer is:
To solve the given problem, we need to evaluate the expression: \[ S = n^3 - (n-1)^3 + (n-1)^3 - (n-2)^3 + (n-2)^3 - (n-3)^3 + \ldots + (-1)^{n-1} 1^3 \] where \( n \) is an odd integer greater than or equal to 1. ### Step-by-Step Solution: 1. **Identify the Pattern**: The expression alternates between positive and negative cubes. The first term is \( n^3 \), followed by \( -(n-1)^3 \), then \( (n-1)^3 \), and so on. 2. **Group the Terms**: We can group the terms in pairs. Notice that each pair consists of a positive cube and a negative cube: \[ S = n^3 - (n-1)^3 + (n-1)^3 - (n-2)^3 + (n-2)^3 - (n-3)^3 + \ldots + (-1)^{n-1} 1^3 \] This can be rewritten as: \[ S = n^3 + \left( - (n-1)^3 + (n-1)^3 \right) + \left( - (n-2)^3 + (n-2)^3 \right) + \ldots + (-1)^{n-1} 1^3 \] 3. **Simplify the Expression**: The terms \( -(n-1)^3 + (n-1)^3 \) cancel out, and so do \( -(n-2)^3 + (n-2)^3 \), and so on. Thus, we only need to consider the first term: \[ S = n^3 + \text{(remaining terms cancel out)} \] 4. **Count the Remaining Terms**: Since \( n \) is odd, the number of terms in the series is \( n \). The last term, when \( n \) is odd, will be \( 1^3 \) with a negative sign. 5. **Final Calculation**: The only term that remains is \( n^3 \) from the first term, and the last term contributes \( -1^3 \): \[ S = n^3 - 1 \] 6. **Conclusion**: Thus, the value of the expression is: \[ S = n^3 - 1 \] ### Final Answer: The value of the expression is \( n^3 - 1 \).

To solve the given problem, we need to evaluate the expression: \[ S = n^3 - (n-1)^3 + (n-1)^3 - (n-2)^3 + (n-2)^3 - (n-3)^3 + \ldots + (-1)^{n-1} 1^3 \] where \( n \) is an odd integer greater than or equal to 1. ### Step-by-Step Solution: ...
Promotional Banner

Topper's Solved these Questions

  • SEQUENCES AND SERIES

    ARIHANT MATHS ENGLISH|Exercise Exercise (More Than One Correct Option Type Questions)|15 Videos
  • SEQUENCES AND SERIES

    ARIHANT MATHS ENGLISH|Exercise Exercise (Passage Based Questions)|24 Videos
  • SEQUENCES AND SERIES

    ARIHANT MATHS ENGLISH|Exercise Exercise For Session 7|7 Videos
  • PROPERTIES AND SOLUTION OF TRIANGLES

    ARIHANT MATHS ENGLISH|Exercise Exercise (Questions Asked In Previous 13 Years Exam)|21 Videos
  • SETS, RELATIONS AND FUNCTIONS

    ARIHANT MATHS ENGLISH|Exercise Exercise (Questions Asked In Previous 13 Years Exam)|12 Videos

Similar Questions

Explore conceptually related problems

If n is n odd integer that is greater than or equal to 3 but not a multiple of 3, then prove that (x+1)^n-x^n-1 is divisible by x^3+x^2+xdot

If n is n odd integer that is greater than or equal to 3 but not a multiple of 3, then prove that (x+1)^n-x^n-1 is divisible by x^3+x^2+xdot

If n is ann integer greater than 1, then a-^(n)C_(1)(a-1)+.^(n)C_(2)(a-2)- . . .+(-1)^(n)(a-n)=

If n is any integer, then the value of (-sqrt(-1))^(4n+3)

For and odd integer n ge 1, n^(3) - (n - 1)^(3) + …… + (- 1)^(n-1) 1^(3)

The value of Sigma_(n=1)^(3) tan^(-1)((1)/(n)) is

If n ge 1 is a positive integer, then prove that 3^(n) ge 2^(n) + n . 6^((n - 1)/(2))

The value of lim_(n -> oo)(1.n+2.(n-1)+3.(n-2)+...+n.1)/(1^2+2^2+...+n^2)

If n is a non zero rational number then show that 1 + n/2 + (n (n - 1))/(2.4) + (n(n-1)(n - 2))/(2.4.6) + ….. = 1 + n/3 + (n (n + 1))/(3.6) + (n (n + 1) (n + 2))/(3.6.9) + ….

Find the sum of the series: 1. n+2.(n-1)+3.(n-2)++(n-1). 2+n .1.

ARIHANT MATHS ENGLISH-SEQUENCES AND SERIES-Exercise (Single Option Correct Type Questions)
  1. The sum to infinity of the series 1+2(1-(1)/(n))+3(1-(1)/(n))^(2)+ ....

    Text Solution

    |

  2. If log(3)2,log(3)(2^(x)-5) and log(3)(2^(x)-7/2) are in A.P., then x i...

    Text Solution

    |

  3. If x,y,z be three positive prime numbers. The progression in which sqr...

    Text Solution

    |

  4. If n is an odd integer greater than or equal to 1, then the value of n...

    Text Solution

    |

  5. If the sides of a right angled triangle are in A.P then the sines of t...

    Text Solution

    |

  6. The 6th term of an AP is equal to 2, the value of the common differenc...

    Text Solution

    |

  7. If the arithmetic progression whose common difference is nonzero the ...

    Text Solution

    |

  8. The coefficient of x^(n) in the expansion of (1+x)(1-x)^(n) is

    Text Solution

    |

  9. Consider the pattern shown below: {:(" Row ",1,1,,,),(" Row ",2,3,5,...

    Text Solution

    |

  10. Let a(n) be the nth term of an AP, if sum(r=1)^(100)a(2r)= alpha " and...

    Text Solution

    |

  11. If a(1),a(2),a(3),a(4),a(5) are in HP, then a(1)a(2)+a(2)a(3)+a(3)a(4)...

    Text Solution

    |

  12. If a,b,c and d are four positive real numbers such that abcd=1 , what ...

    Text Solution

    |

  13. If a,b,c are in AP and (a+2b-c)(2b+c-a)(c+a-b)=lambdaabc, then lambda...

    Text Solution

    |

  14. If a(1),a(2),a(3)"....." are in GP with first term a and common ratio ...

    Text Solution

    |

  15. If the sum of first 10 terms of an A.P. is 4 times the sum of its firs...

    Text Solution

    |

  16. If cos(x-y),cosx and "cos"(x+y) are in H.P., then cosxsec(y/2) is

    Text Solution

    |

  17. If eleven A.M. s are inserted between 28 and 10, then find the number ...

    Text Solution

    |

  18. If x >1,y >1,a n dz >1 are in G.P., then 1/(1+lnx),1/(1+l ny)a n d1/(1...

    Text Solution

    |

  19. The minimum value of ((a^2 +3a+1)(b^2+3b + 1)(c^2+ 3c+ 1))/(abc)The mi...

    Text Solution

    |

  20. Leta(1),a(2),"...." be in AP and q(1),q(2),"...." be in GP. If a(1)=q(...

    Text Solution

    |