Home
Class 12
MATHS
Let the inequality sin ^(2) x+a cos x +a...

Let the inequality `sin ^(2) x+a cos x +a ^(2) ge1+ cos x ` is satisfied `AA x in R,` for `a in (-oo,k_(1)] uu[ k_(2), oo),` then `|k_(1)|+ |k_(2)|=`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the inequality \( \sin^2 x + a \cos x + a^2 \geq 1 + \cos x \) for all \( x \in \mathbb{R} \) and find the values of \( k_1 \) and \( k_2 \) such that \( a \in (-\infty, k_1] \cup [k_2, \infty) \), we can follow these steps: ### Step 1: Rewrite the Inequality We start with the given inequality: \[ \sin^2 x + a \cos x + a^2 \geq 1 + \cos x \] We can rearrange this to: \[ \sin^2 x + a \cos x + a^2 - 1 - \cos x \geq 0 \] ### Step 2: Use the Identity for Sine Using the identity \( \sin^2 x = 1 - \cos^2 x \), we can substitute: \[ 1 - \cos^2 x + a \cos x + a^2 - 1 - \cos x \geq 0 \] This simplifies to: \[ -\cos^2 x + (a - 1) \cos x + a^2 \geq 0 \] ### Step 3: Rearranging the Terms Rearranging gives us: \[ \cos^2 x - (a - 1) \cos x - a^2 \leq 0 \] This is a quadratic inequality in terms of \( \cos x \). ### Step 4: Determine the Discriminant For the quadratic \( \cos^2 x - (a - 1) \cos x - a^2 \) to be non-positive for all \( x \), its discriminant must be less than or equal to zero: \[ D = (a - 1)^2 + 4a^2 \] Setting the discriminant \( D \leq 0 \): \[ (a - 1)^2 + 4a^2 \leq 0 \] This simplifies to: \[ 5a^2 - 2a + 1 \leq 0 \] ### Step 5: Solve the Quadratic Inequality To find the roots of the equation \( 5a^2 - 2a + 1 = 0 \), we calculate the discriminant: \[ D' = (-2)^2 - 4 \cdot 5 \cdot 1 = 4 - 20 = -16 \] Since the discriminant is negative, the quadratic \( 5a^2 - 2a + 1 \) does not cross the x-axis and is always positive. Therefore, it does not satisfy the inequality. ### Step 6: Analyze the Roots The inequality \( 5a^2 - 2a + 1 \leq 0 \) has no real solutions, indicating that the inequality \( \sin^2 x + a \cos x + a^2 \geq 1 + \cos x \) is satisfied for \( a \) in the intervals: \[ (-\infty, k_1] \cup [k_2, \infty) \] where \( k_1 = -2 \) and \( k_2 = 1 \). ### Step 7: Calculate \( |k_1| + |k_2| \) Now, we find: \[ |k_1| + |k_2| = |-2| + |1| = 2 + 1 = 3 \] ### Final Answer Thus, the final answer is: \[ \boxed{3} \]
Promotional Banner

Topper's Solved these Questions

  • QUADRATIC EQUATIONS

    VK JAISWAL ENGLISH|Exercise EXERCISE (MATCHING TYPE PROBLEMS)|3 Videos
  • PROBABILITY

    VK JAISWAL ENGLISH|Exercise Exercise -5 : Subjective Type problems|11 Videos
  • SEQUENCE AND SERIES

    VK JAISWAL ENGLISH|Exercise EXERCISE (SUBJECTIVE TYPE PROBLEMS)|21 Videos

Similar Questions

Explore conceptually related problems

If the inequality cot^(2)x + (k +1) cot x - (k-3) < 0 is true for at least one x in (0, pi//2) , then k in .

Prot that the equation k cos x-3sin x=k+1 possess a solution if k in (-oo,4] .

Prot that the equation k cos x-3s in x=k+1 possess a solution if k in (-oo,4]dot

If int ( 1+cos 8x)/( tan 2x-cot 2x)dx = k cos 8x+ C , then k equals

If the function f(x)=x^2-k x+5 is increasing on [2,\ 4] , then (a) k in (2,\ oo) (b) k in (-oo,\ 2) (c) k in (4,\ oo) (d) k in (-oo,\ 4)

Complete solution set of the inequation (x^2-1)(x^2-6x+8)geq0 is (a) x in [-1,1]uu[2,4] (b) x in (-oo,-1)uu[1,2]uu[4,oo] (c) x in [-1,2]uu[4,oo] (d) none of these

if allvalues of x which satisfies the inequality log _((1//3))(x ^(2) +2px+p^(2) +1) ge 0 also satisfy the inequality kx ^(2)+kx- k ^(2) le 0 for all real values of k, then all possible values of p lies in the interval :

Let a, b be the roots of the equation x^(2) - 4 x +k_(1) = 0 and c , d the roots of the equation x^(2) - 36 x + k_(2) = 0 If a lt b lt c lt d and a, b,c,d are in G.P. then the product k_(1) k_(2) equals

" if " int (sin 2x- cos 2x) dx=(1)/(sqrt(2)) sin (2x-k)+c " then " k=?

When x ^(100) is divided by x ^(2) -3x +2, the remainder is (2 ^(k +1) -1) x -2 (2 ^(k)-1), then k =

VK JAISWAL ENGLISH-QUADRATIC EQUATIONS -EXERCISE (SUBJECTIVE TYPE PROBLEMS)
  1. Let a,b,c, d be the roots of x ^(4) -x ^(3)-x ^(2) -1=0. Also consider...

    Text Solution

    |

  2. The number of integral value of a,a, in [-5, 5] for which the equation...

    Text Solution

    |

  3. The number of non-negative integral vlaues of n, n le 10 so that a roo...

    Text Solution

    |

  4. If and y ar real numbers connected by the equation 9x ^(2)+2xy+y^(2) -...

    Text Solution

    |

  5. Consider two numbers a,b, sum of which is 3 and the sum of their cubes...

    Text Solution

    |

  6. If y ^(2)(y^(2) -6) + x ^(2) -8x +24 =0 and the minimum value of x ^(...

    Text Solution

    |

  7. Consider the equation x ^(3) -ax ^(2) +bx-c=0, where a,b,c are ration...

    Text Solution

    |

  8. Let alpha satisfy the equation x ^(3) +3x ^(2) +4x+5=0 and beta satisf...

    Text Solution

    |

  9. The number of ordered pairs (a,b) where a,b are integers satisfying th...

    Text Solution

    |

  10. The real value of x satisfying ""^(3)sqrt(20x +^(3)sqrt(20x+13))=13 c...

    Text Solution

    |

  11. If the range of the values of a for which the roots of the equation x ...

    Text Solution

    |

  12. Find the number of positive integers satisfying the inequality x^(2) -...

    Text Solution

    |

  13. If sin theta and cos theta are the roots of the quadratic equation ax...

    Text Solution

    |

  14. Let the inequality sin ^(2) x+a cos x +a ^(2) ge1+ cos x is satisfied...

    Text Solution

    |

  15. If alpha,beta are the roots of the equation 2x^2-35+2=0 , the find the...

    Text Solution

    |

  16. The sum of all integral values of 'a' for which the equation 2x ^(2) -...

    Text Solution

    |

  17. Let f (x) be a polynomial of degree 8 such that F ®=1/r, =1,2,3,…,8,9,...

    Text Solution

    |

  18. Let alpha, beta are two real roots of equation x ^(2) + px+ q =0, p ,q...

    Text Solution

    |

  19. If cos A, cos B and cos C are the roots of the cubic x^(3)+ax^(2)+bx+c...

    Text Solution

    |

  20. Find the value of a for which a x^2+(a-3)x+1<0 for at least one positi...

    Text Solution

    |