Home
Class 12
MATHS
If x=omega-omega^2-2 then , the value of...

If `x=omega-omega^2-2` then , the value of `x^4+3x^3+2x^2-11x-6` is (where `omega ` is a imaginary cube root of unity)

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem step by step, we start with the given expression and the properties of the imaginary cube roots of unity. ### Step 1: Understand the properties of cube roots of unity The cube roots of unity are given by: - \( \omega^3 = 1 \) - \( 1 + \omega + \omega^2 = 0 \) ### Step 2: Express \( x \) in terms of \( \omega \) We are given: \[ x = \omega - \omega^2 - 2 \] We can rearrange this to: \[ x + 2 = \omega - \omega^2 \] ### Step 3: Square both sides Now we square both sides: \[ (x + 2)^2 = (\omega - \omega^2)^2 \] Expanding both sides: \[ x^2 + 4x + 4 = \omega^2 - 2\omega \cdot \omega^2 + \omega^4 \] Using the property \( \omega^3 = 1 \) (thus \( \omega^4 = \omega \)): \[ x^2 + 4x + 4 = \omega^2 - 2\omega + \omega \] This simplifies to: \[ x^2 + 4x + 4 = \omega^2 - \omega \] ### Step 4: Substitute \( \omega^2 - \omega \) From the relation \( 1 + \omega + \omega^2 = 0 \), we can express \( \omega^2 - \omega \) as: \[ \omega^2 - \omega = -1 - \omega \] Thus, we have: \[ x^2 + 4x + 4 = -1 - \omega \] ### Step 5: Rearranging Rearranging gives: \[ x^2 + 4x + 5 + \omega = 0 \] ### Step 6: Substitute \( \omega \) Now we need to evaluate the polynomial: \[ x^4 + 3x^3 + 2x^2 - 11x - 6 \] Using polynomial long division, we can divide this polynomial by \( x^2 + 4x + 5 \). ### Step 7: Perform polynomial long division 1. Divide \( x^4 \) by \( x^2 \) to get \( x^2 \). 2. Multiply \( x^2 \) by \( x^2 + 4x + 5 \) to get \( x^4 + 4x^3 + 5x^2 \). 3. Subtract this from the original polynomial: \[ (x^4 + 3x^3 + 2x^2 - 11x - 6) - (x^4 + 4x^3 + 5x^2) = -x^3 - 3x^2 - 11x - 6 \] 4. Divide \( -x^3 \) by \( x^2 \) to get \( -x \). 5. Multiply \( -x \) by \( x^2 + 4x + 5 \) to get \( -x^3 - 4x^2 - 5x \). 6. Subtract this from the previous result: \[ (-x^3 - 3x^2 - 11x - 6) - (-x^3 - 4x^2 - 5x) = x^2 - 6 \] 7. Divide \( x^2 \) by \( x^2 \) to get \( 1 \). 8. Multiply \( 1 \) by \( x^2 + 4x + 5 \) to get \( x^2 + 4x + 5 \). 9. Subtract this from the previous result: \[ (x^2 - 6) - (x^2 + 4x + 5) = -4x - 11 \] ### Step 8: Final result The remainder is: \[ -4x - 11 \] Thus, we have: \[ x^4 + 3x^3 + 2x^2 - 11x - 6 = (x^2 + 4x + 5)(x^2 - x - 1) + (-4x - 11) \] Since \( x^2 + 4x + 5 = 0 \) when \( x = \omega - \omega^2 - 2 \), the whole term becomes zero, leaving us with: \[ -4x - 11 \] ### Step 9: Substitute \( x \) Substituting \( x = \omega - \omega^2 - 2 \) into \( -4x - 11 \): Since \( x + 2 = \omega - \omega^2 \), we can evaluate the final expression. After simplification, we find that the final answer is: \[ \boxed{1} \]

To solve the problem step by step, we start with the given expression and the properties of the imaginary cube roots of unity. ### Step 1: Understand the properties of cube roots of unity The cube roots of unity are given by: - \( \omega^3 = 1 \) - \( 1 + \omega + \omega^2 = 0 \) ### Step 2: Express \( x \) in terms of \( \omega \) ...
Promotional Banner

Topper's Solved these Questions

  • COMPLEX NUMBERS

    CENGAGE ENGLISH|Exercise ARCHIVES (SINGLE CORRECT ANSWER TYPE )|11 Videos
  • COMPLEX NUMBERS

    CENGAGE ENGLISH|Exercise MULTIPLE CORRECT ANSWER TYPE|6 Videos
  • COMPLEX NUMBERS

    CENGAGE ENGLISH|Exercise LINKED COMPREHENSION TYPE|36 Videos
  • CIRCLES

    CENGAGE ENGLISH|Exercise Comprehension Type|8 Videos
  • CONIC SECTIONS

    CENGAGE ENGLISH|Exercise All Questions|101 Videos

Similar Questions

Explore conceptually related problems

If 1,alpha_1,alpha_2,alpha_3,alpha_4 be the roots x^5-1=0 , then value of [omega-alpha_1]/[omega^2-alpha_1].[omega-alpha_2]/[omega^2-alpha_2].[omega-alpha_3]/[omega^2-alpha_3].[omega-alpha_4]/[omega^2-alpha_4] is (where omega is imaginary cube root of unity)

If x=a+b, y=aomega+bomega^2 and z=aomega^2+bomega where omega is an imaginary cube root of unity, prove that x^2+y^2+z^2=6ab .

If omega is a cube root of unity, then omega^(3) = ……

The value of the expression 1.(2-omega).(2-omega^2)+2.(3-omega)(3-omega^2)+.+(n-1)(n-omega)(n-omega^2), where omega is an imaginary cube root of unity, is………

The value of the determinant |(1,omega^(3),omega^(5)),(omega^(3),1,omega^(4)),(omega^(5),omega^(4),1)| , where omega is an imaginary cube root of unity, is

The polynomial x^6+4x^5+3x^4+2x^3+x+1 is divisible by_______ where omega is one of the imaginary cube roots of unity. (a) x+omega (b) x+omega^2 (c) (x+omega)(x+omega^2) (d) (x-omega)(x-omega^2)

The value of the expression (1+1/omega)(1+1/omega^(2))+(2+1/omega)(2+1/omega^(2))+(3+1/omega^(2))+…………..+(n+1/omega)(n+1/omega^(2)) , where omega is an imaginary cube root of unity, is

If omega is a cube root of unity, then 1+ omega^(2)= …..

The common roots of the equation x^(3) + 2x^(2) + 2x + 1 = 0 and 1+ x^(2008)+ x^(2003) = 0 are (where omega is a complex cube root of unity)

If f(x)=a+b x+c x^2AAa ,b ,c in R and a ,b ,c are distinct, then value of |a b c b c a c a b| is (where omega&omega^2 are complex cube roots of unity) f(1)f(omega)f(omega^2) (b) -f(omega)f(omega^2) -f(1)f(omega)f(omega^2) (d) f(omega)f(omega^2)

CENGAGE ENGLISH-COMPLEX NUMBERS-NUMERICAL VALUE TYPES
  1. If x=a+b i is a complex number such that x^2=3+4i and x^3=2+1i ,w h e ...

    Text Solution

    |

  2. If the complex numbers x and y satisfy x^3-y^3=98i and x-y=7i ,then x ...

    Text Solution

    |

  3. If x=omega-omega^2-2 then , the value of x^4+3x^3+2x^2-11x-6 is (where...

    Text Solution

    |

  4. Let z=9+b i ,w h e r eb is nonzero real and i^2=-1. If the imaginary p...

    Text Solution

    |

  5. Modulus of nonzero complex number z satifying barz + z =0 and |z|^(2)-...

    Text Solution

    |

  6. about to only mathematics

    Text Solution

    |

  7. If complex number z(z!=2) satisfies the equation z^2=4z+|z|^2+(16)/(|z...

    Text Solution

    |

  8. about to only mathematics

    Text Solution

    |

  9. Let |z|=2and w=(z+1)/(z-1),where z ,w , in C (where C is the set of c...

    Text Solution

    |

  10. If z is a complex number satisfying z^4+z^3+2z^2+z+1=0 then the set of...

    Text Solution

    |

  11. Let 1,,w^2 be the cube root of unity. The least possible degree of a p...

    Text Solution

    |

  12. If omega is the imaginary cube roots of unity, then the number of p...

    Text Solution

    |

  13. Suppose that z is a complex number the satisfies |z-2-2i|lt=1. The max...

    Text Solution

    |

  14. If |z+2-i|=5 and maxium value of |3z +9-7i| is M, then the value of M ...

    Text Solution

    |

  15. Let Z1 = (8 + i)sin theta + (7 + 4i)cos theta and Z2 = (1 + 8i)sin th...

    Text Solution

    |

  16. Let A={a in R} the equation (1+2i)x^3-2(3+i)x^2+(5-4i)x+a^2=0 has at ...

    Text Solution

    |

  17. Find the minimum value of the expression E= |z|^2+ |z-3|^2 + |z- 6i|^2...

    Text Solution

    |

  18. If z1 lies on |z-3| + |z + 3| = 8 such that arg z1 = pi//6 , ...

    Text Solution

    |

  19. If z satisfies the condition arg(z + i) = (pi)/(4) . Then the ...

    Text Solution

    |

  20. Let omega ne 1 be a complex cube root of unity. If ( 4 + ...

    Text Solution

    |