Home
Class 12
MATHS
Let alpha be the real and beta, gamma be...

Let `alpha` be the real and `beta, gamma` be the complex roots of `x^(3) + 3x^(2) + 3x + 28 = 0`, then `|alpha + 2 beta + 2 gamma|` = _________________.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of \( | \alpha + 2\beta + 2\gamma | \) where \( \alpha \) is the real root and \( \beta, \gamma \) are the complex roots of the polynomial \( x^3 + 3x^2 + 3x + 28 = 0 \). ### Step-by-step Solution: 1. **Identify the polynomial**: We have the polynomial \( f(x) = x^3 + 3x^2 + 3x + 28 \). 2. **Find the sum of the roots**: According to Vieta's formulas, the sum of the roots \( \alpha + \beta + \gamma = -\frac{b}{a} = -\frac{3}{1} = -3 \). 3. **Determine the nature of the roots**: Since the polynomial is cubic and has a positive leading coefficient, we can analyze its behavior to find the roots. We will check for real roots by evaluating the polynomial at various points. 4. **Evaluate the polynomial at \( x = -4 \)**: \[ f(-4) = (-4)^3 + 3(-4)^2 + 3(-4) + 28 = -64 + 48 - 12 + 28 = 0. \] Thus, \( \alpha = -4 \) is a real root. 5. **Find \( \beta + \gamma \)**: Using the sum of the roots: \[ \alpha + \beta + \gamma = -3 \implies -4 + \beta + \gamma = -3 \implies \beta + \gamma = 1. \] 6. **Calculate \( \alpha + 2\beta + 2\gamma \)**: \[ \alpha + 2\beta + 2\gamma = -4 + 2(\beta + \gamma) = -4 + 2(1) = -4 + 2 = -2. \] 7. **Find the absolute value**: \[ | \alpha + 2\beta + 2\gamma | = |-2| = 2. \] ### Final Answer: \[ | \alpha + 2\beta + 2\gamma | = 2. \]
Promotional Banner

Topper's Solved these Questions

  • COMPLEX NUMBERS

    MCGROW HILL PUBLICATION|Exercise QUESTIONS FROM PREVIOUS YEARS. AIEEE/JEE MAIN PAPERS|58 Videos
  • COMPLEX NUMBERS

    MCGROW HILL PUBLICATION|Exercise QUESTIONS FROM PREVIOUS YEARS. B-ARCHITECTURE ENTRANCE EXAMINATION PAPER|17 Videos
  • COMPLEX NUMBERS

    MCGROW HILL PUBLICATION|Exercise EXERCISE LEVEL 21|1 Videos
  • CIRCLES AND SYSTEMS OF CIRCLES

    MCGROW HILL PUBLICATION|Exercise QUESTIONS FROM PREVIOUS YEARS. B-ARCHITECTURE ENTRANCE EXAMINATION PAPERS|17 Videos
  • DEFINITE INTEGRALS

    MCGROW HILL PUBLICATION|Exercise Questions from Previous Years. B-Architecture Entrance Examination Papers|18 Videos

Similar Questions

Explore conceptually related problems

If alpha,beta,gamma are the roots of x^(3)-3x^(2)+4x-7=0, then (alpha+2)(beta+2)(gamma+2)=

If alpha,beta,gamma are the roots of x^(3)-2x^(2)+3x-4=0 then sum alpha beta(alpha+beta)=

If alpha,beta,gamma are the roots of x^(3)+2x^(2)+3x+8=0 then (alpha+beta)(beta+gamma)(gamma+alpha)=

Let alpha,beta,gamma be the complex roots of x^(3)-1=0 then,alpha+beta+gamma is equal to

If alpha,beta,gamma are the roots of x^(3)+2x^(2)-3x-1=0 then alpha^(-2)+beta^(-2)+gamma^(-2)=

If alpha beta gamma are roots of x^(3)+x^(2)-5x-1=0 then alpha + beta + gamma is equal to

If alpha,beta,gamma are the roots of the equation 2x^(3)x^(2)+x-1=0 then alpha^(2)+beta^(2)+gamma^(2)=

If alpha,beta,gamma are the roots of x^(3)+x^(2)+x+1=0 then alpha^(3)+beta^(3)+gamma^(3)=

if alpha,beta,gamma are the roots of 2x^(3)-5x^(2)-14x+8=0 then find alpha+beta+gamma

MCGROW HILL PUBLICATION-COMPLEX NUMBERS -EXERCISE NUMERICAL ANSWER TYPE QUESTIONS
  1. Suppose a in R and z in C. "If" |z| = 2 and (z-alpha)/(z+alpha) is pur...

    Text Solution

    |

  2. If alpha an d beta are roots of the equation x^(2)-2x+2=0, then the le...

    Text Solution

    |

  3. Let S = {(2alpha+3i)/(2alpha-3i):alpha in R}. All the points of S lie ...

    Text Solution

    |

  4. Let omega ne 1 be cube root of unity. Suppose (1 + omega)^(2023) = A +...

    Text Solution

    |

  5. If (7+i)(z + bar(z))-(4+i)(z-bar(z)) + 116i = 0 then z bar(z) is equal...

    Text Solution

    |

  6. Let C(1) be the curve represented by (2z + i)/(z-2) is purely imaginar...

    Text Solution

    |

  7. Let a = 3 + 4i, z(1) and z(2) be two complex numbers such that |z(1)| ...

    Text Solution

    |

  8. Let alpha be the real and beta, gamma be the complex roots of x^(3) + ...

    Text Solution

    |

  9. Let z = ((2)/(i + sqrt(3)))^(200)+((2)/(i-sqrt(3)))^(200),"then" |z + ...

    Text Solution

    |

  10. Let z be a non-zero complex number such that area of the triangle with...

    Text Solution

    |

  11. Suppose x, y in R. If x^(2) + y + 4i is conjugate of -3 + x^(2) yi, th...

    Text Solution

    |

  12. All the roots of the equation x^(11) - x^(6) - x^(5) + 1 = 0 lie on a ...

    Text Solution

    |

  13. If 13 e^(i tan^(-1)(5//12))= a+ib, then |a| + |b| is equal to .

    Text Solution

    |

  14. Suppose, a, b, c ge 0, c ne 1, a^(2) + b^(2) + c^(2) = c. If |(a+ib)/(...

    Text Solution

    |

  15. Let z(1), z(2), z(3) be the roots of iz^(3) + 5z^(2) - z + 5i = 0, the...

    Text Solution

    |

  16. Let S = {z in C : z^(2) = 4 (i bar(z))^(2)},"then" sum(z in S)|z+(1)/(...

    Text Solution

    |

  17. Let z = (1)/(2) (sqrt(3) + i),"then" |(z^(101)+i^(103))^(105)|= .

    Text Solution

    |

  18. If alpha = cos((8pi)/11)+i sin ((8pi)/11) then Re(alpha + alpha^2+alph...

    Text Solution

    |

  19. Eccentricity of conic |z - 5i| + |z + 5i| = 25 is .

    Text Solution

    |

  20. If alpha is a non-real root of x^6=1 then (alpha^5+alpha^3+alpha+1)/(a...

    Text Solution

    |