Home
Class 12
MATHS
Let px^(2)+qx+r=0 be a quadratic equatio...

Let `px^(2)+qx+r=0` be a quadratic equation `(p,q,r in R)` such that its roots are `alpha and beta`. If `p+q+rlt0,p-q+rlt0 and r gt0`, then the value of `[alpha]+[beta]` is (where[x] denotes the greatest integer x)________.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem step by step, we will analyze the given quadratic equation and the conditions provided. ### Step 1: Understand the Quadratic Equation The given quadratic equation is: \[ px^2 + qx + r = 0 \] where \( p, q, r \) are real numbers and the roots are \( \alpha \) and \( \beta \). ### Step 2: Use Vieta's Formulas According to Vieta's formulas, the sum of the roots \( \alpha + \beta \) can be expressed as: \[ \alpha + \beta = -\frac{q}{p} \] ### Step 3: Analyze the Conditions We have the following conditions: 1. \( p + q + r < 0 \) 2. \( p - q + r < 0 \) 3. \( r > 0 \) ### Step 4: Evaluate the Conditions 1. From \( p + q + r < 0 \), we can infer that \( p + q < -r \). 2. From \( p - q + r < 0 \), we can infer that \( p - q < -r \). 3. Since \( r > 0 \), this means \( -r < 0 \). ### Step 5: Substitute Values Now, let's evaluate the function \( f(x) = px^2 + qx + r \) at specific points: - When \( x = 0 \): \[ f(0) = r > 0 \] - When \( x = 1 \): \[ f(1) = p + q + r < 0 \] - When \( x = -1 \): \[ f(-1) = p - q + r < 0 \] ### Step 6: Identify the Roots From the evaluations: - Since \( f(0) > 0 \) and \( f(1) < 0 \), by the Intermediate Value Theorem, there is a root \( \alpha \) in the interval \( (0, 1) \). - Since \( f(-1) < 0 \) and \( f(0) > 0 \), there is a root \( \beta \) in the interval \( (-1, 0) \). ### Step 7: Determine the Greatest Integer Values - Since \( \alpha \) lies between \( 0 \) and \( 1 \), the greatest integer value \( [\alpha] = 0 \). - Since \( \beta \) lies between \( -1 \) and \( 0 \), the greatest integer value \( [\beta] = -1 \). ### Step 8: Calculate the Final Result Now, we can find: \[ [\alpha] + [\beta] = 0 + (-1) = -1 \] ### Conclusion Thus, the value of \( [\alpha] + [\beta] \) is: \[ \boxed{-1} \]

To solve the problem step by step, we will analyze the given quadratic equation and the conditions provided. ### Step 1: Understand the Quadratic Equation The given quadratic equation is: \[ px^2 + qx + r = 0 \] where \( p, q, r \) are real numbers and the roots are \( \alpha \) and \( \beta \). ### Step 2: Use Vieta's Formulas ...
Promotional Banner

Topper's Solved these Questions

  • THEORY OF EQUATIONS

    CENGAGE ENGLISH|Exercise Archives JEE MAIN (single correct Answer Type )|7 Videos
  • THEORY OF EQUATIONS

    CENGAGE ENGLISH|Exercise JEE ADVANCED (Single Correct Type )|5 Videos
  • THEORY OF EQUATIONS

    CENGAGE ENGLISH|Exercise MATRIX MATCH TYPE|6 Videos
  • STRAIGHT LINES

    CENGAGE ENGLISH|Exercise ARCHIVES (NUMERICAL VALUE TYPE)|1 Videos
  • THREE DIMENSIONAL GEOMETRY

    CENGAGE ENGLISH|Exercise All Questions|294 Videos

Similar Questions

Explore conceptually related problems

If rlt0 and (4r-4)^(2)=36 , what is the value of r?

Let p, q, r in R and r gt p gt 0 . If the quadratic equation px^(2) + qx + r = 0 has two complex roots alpha and beta , then |alpha|+|beta| , is

Let alpha and beta be the roots of equation px^2 + qx + r = 0 , p != 0 .If p,q,r are in A.P. and 1/alpha+1/beta=4 , then the value of |alpha-beta| is :

Let alpha and beta be the roots of equation px^2 + qx + r = 0 , p != 0 .If p,q,r are in A.P. and 1/alpha+1/beta=4 , then the value of |alpha-beta| is :

If alpha , beta , gamma are the roots of x^3 +px^2 +qx +r=0 then find sum alpha^2 beta^2

If alpha, beta be the roots of the equation x^2-px+q=0 then find the equation whose roots are q/(p-alpha) and q/(p-beta)

Let p, q in R . If 2- sqrt3 is a root of the quadratic equation, x^(2)+px+q=0, then

If p,q are roots of the quadratic equation x^(2)-10rx -11s =0 and r,s are roots of x^(2)-10px -11q=0 then find the value of p+q +r+s.

if p and q are non zero constants, the equation x^2+px+q=0 has roots alpha and beta then the equation qx^2+px+1=0 has roots

If one root of the quadratic equation px^2 +qx + r = 0 (p != 0) is a surd sqrta/(sqrta+sqrt(a-b), where p, q, r; a, b are all rationals then the other root is -

CENGAGE ENGLISH-THEORY OF EQUATIONS-NUMERICAL VALUE TYPE
  1. Let P(x)=5/4+6x-9x^2a n dQ(y)=-4y^2+4y+(13)/2dot if there exists uniqu...

    Text Solution

    |

  2. If equation x^4-(3m+2)x^2+m^2=0(m >0) has four real solutions which ar...

    Text Solution

    |

  3. If the equation 2x^2+4x y+7y^2-12 x-2y+t=0, where t is a parameter has...

    Text Solution

    |

  4. Let P(x0=x^3-8x^2+c x-d be a polynomial with real coefficients and wit...

    Text Solution

    |

  5. Let P(x)=x^4+a x^3+b x^2+c x+d be a polynomial such that P(1)=1,P(2)=8...

    Text Solution

    |

  6. Suppose a ,b ,c in I such that the greatest common divisor for x^2+a ...

    Text Solution

    |

  7. Integral part of the product of non-real roots of equation x^(4)-4x^(3...

    Text Solution

    |

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

    Text Solution

    |

  9. If the roots of the cubic, x^3+a x^2+b x+c=0 are three consecutive pos...

    Text Solution

    |

  10. The function kf(x)=a x^3+b x^2+c x+d has three positive roots. If the ...

    Text Solution

    |

  11. If b^(2)-4acle0 ("where" ane0 and a,b,c,x,y in R) satisfies the system...

    Text Solution

    |

  12. If (a^(2)-14a+13)x^(2)+(a+2)x-2=0 does not have two distinct real root...

    Text Solution

    |

  13. Let px^(2)+qx+r=0 be a quadratic equation (p,q,r in R) such that its r...

    Text Solution

    |

  14. Let x^2+y^2+x y+1geqa(x+y)AAx ,y in R , then the number of possible i...

    Text Solution

    |

  15. function f , R ->R , f(x) = (3x^2+mx+n)/(x^2+1) , if the range of func...

    Text Solution

    |

  16. If a ,b ,c are non-zero real numbers, then find the minimum value of t...

    Text Solution

    |

  17. If a ,b , in R such that a+b=1a n d(1-2a b0(a 63+b^3)=12 . The value ...

    Text Solution

    |

  18. If the cubic 2x^3-9x^2+12 x+k=0 has two equal roots then minimum value...

    Text Solution

    |

  19. Let a ,b ,a n dc be distinct nonzero real numbers such that (1-a^3)/a=...

    Text Solution

    |

  20. Evaluate : (i) i^(135) (ii) i^(-47) (iii) (-sqrt(-1))^(4n +3)...

    Text Solution

    |