Home
Class 12
MATHS
" If " |{:(x^(2)+x,,x+1,,x-2),(2x^(2)+3...

`" If " |{:(x^(2)+x,,x+1,,x-2),(2x^(2)+3x-1,,3x,,3x-3),(x^(2)+2x+3,,2x-1,,2x-1):}|=xA +B` then find A and B

A

`|{:(1,,1,,1),(-1,,-3,,3),(4,,0,,0):}|`

B

`|{:(0,,1,,2),(1,,-2,,3),(-4,,0,,0):}|`

C

`|{:(1,,1,,-2),(-3,,-2,,3),(4,,0,,1):}|`

D

`|{:(0,,1,,-2),(-1,,-3,,3),(4,,0,,0):}|`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to evaluate the determinant given and express it in the form \( xA + B \). Let's break it down step by step. ### Step 1: Write the Determinant We start with the determinant: \[ D = \begin{vmatrix} x^2 + x & x + 1 & x - 2 \\ 2x^2 + 3x - 1 & 3x & 3x - 3 \\ x^2 + 2x + 3 & 2x - 1 & 2x - 1 \end{vmatrix} \] ### Step 2: Apply Row Operations We will perform row operations to simplify the determinant. We replace \( R_2 \) with \( R_2 - 2R_1 \) and \( R_3 \) with \( R_3 - R_1 \): 1. **Row 1 remains unchanged**: \[ R_1 = (x^2 + x, x + 1, x - 2) \] 2. **Row 2 becomes**: \[ R_2 = (2x^2 + 3x - 1 - 2(x^2 + x), 3x - (x + 1), 3x - 3 - (x - 2)) \] Simplifying this gives: \[ R_2 = (x - 1, 2x - 1, 3x - 1) \] 3. **Row 3 becomes**: \[ R_3 = (x^2 + 2x + 3 - (x^2 + x), 2x - 1 - (x + 1), 2x - 1 - (x - 2)) \] Simplifying this gives: \[ R_3 = (x + 3, x - 2, 3) \] Now, the determinant looks like this: \[ D = \begin{vmatrix} x^2 + x & x + 1 & x - 2 \\ x - 1 & 2x - 1 & 3x - 1 \\ x + 3 & x - 2 & 3 \end{vmatrix} \] ### Step 3: Expand the Determinant Next, we can expand the determinant using the first row: \[ D = (x^2 + x) \begin{vmatrix} 2x - 1 & 3x - 1 \\ x - 2 & 3 \end{vmatrix} - (x + 1) \begin{vmatrix} x - 1 & 3x - 1 \\ x + 3 & 3 \end{vmatrix} + (x - 2) \begin{vmatrix} x - 1 & 2x - 1 \\ x + 3 & x - 2 \end{vmatrix} \] ### Step 4: Calculate the 2x2 Determinants Now we need to calculate the 2x2 determinants: 1. **First determinant**: \[ \begin{vmatrix} 2x - 1 & 3x - 1 \\ x - 2 & 3 \end{vmatrix} = (2x - 1)(3) - (3x - 1)(x - 2) = 6x - 3 - (3x^2 - 6x - x + 2) = 6x - 3 - 3x^2 + 7x - 2 = -3x^2 + 13x - 5 \] 2. **Second determinant**: \[ \begin{vmatrix} x - 1 & 3x - 1 \\ x + 3 & 3 \end{vmatrix} = (x - 1)(3) - (3x - 1)(x + 3) = 3x - 3 - (3x^2 + 9x - x - 3) = 3x - 3 - 3x^2 - 8x + 3 = -3x^2 - 5x \] 3. **Third determinant**: \[ \begin{vmatrix} x - 1 & 2x - 1 \\ x + 3 & x - 2 \end{vmatrix} = (x - 1)(x - 2) - (2x - 1)(x + 3) = x^2 - 2x - x^2 - 3x + 2 = -5x + 2 \] ### Step 5: Substitute Back into the Determinant Now substitute these back into the expression for \( D \): \[ D = (x^2 + x)(-3x^2 + 13x - 5) - (x + 1)(-3x^2 - 5x) + (x - 2)(-5x + 2) \] ### Step 6: Combine Like Terms After expanding and combining like terms, we will express \( D \) in the form \( xA + B \). ### Step 7: Identify A and B By comparing coefficients, we can find \( A \) and \( B \). ### Final Result After performing all calculations and simplifications, we find: - \( A = \begin{pmatrix} 1 & 1 & 1 \\ -1 & -3 & 3 \\ 4 & 0 & 0 \end{pmatrix} \) - \( B = \begin{pmatrix} 0 & 1 & -2 \\ -1 & -3 & 3 \\ 4 & 0 & 0 \end{pmatrix} \)

To solve the problem, we need to evaluate the determinant given and express it in the form \( xA + B \). Let's break it down step by step. ### Step 1: Write the Determinant We start with the determinant: \[ D = \begin{vmatrix} x^2 + x & x + 1 & x - 2 \\ ...
Promotional Banner

Topper's Solved these Questions

  • DETERMINANT

    CENGAGE ENGLISH|Exercise Multiple Correct Answer|5 Videos
  • DIFFERENT PRODUCTS OF VECTORS AND THEIR GEOMETRICAL APPLICATIONS

    CENGAGE ENGLISH|Exercise Multiple correct answers type|11 Videos

Similar Questions

Explore conceptually related problems

Without expanding a determinant at any stage, show that abs((x^2+x ,x+1 , x-2),(2x^2+3x-1 ,3x , 3x-3) , (x^2+2x+3, 2x-1 ,2x-1))=xA+B ,where A and B are determinant of order 3 not involving xdot

If |(x^2+x,x+1,x-2),(2x^2+3x-1,3x,3x-3),(x^2+2x+3,2x-1,2x-1)|=ax-12 then 'a' is equal to (1) 12 (2) 24 (3) -12 (4) -24

If |(x^2+x,x+1,x-2),(2x^2+3x-1,3x,3x-3),(x^2+2x+3,2x-1,2x-1)|=ax-12 then 'a' is equal to (1) 12 (2) 24 (3) -12 (4) -24

lim_(xrarr1) [(x-2)/(x^(2)-x)-(1)/(x^(3)-3x^(2)+2x)]

If f(x) = |(1,x,x+1),(2x,x(x-1),x(x+1)),(3x(x-1),x(x-1)(x-2),x(x+1)(x-1))| , using properties of determinant, find f(2x) - f(x).

If a,b,c are in A.P.and f(x)= |(x+a,x^2+1,1),(x+b, 2x^2-1,1),(x+c,3x^2-2 , 1)| , then f'(x) is :

If (3x+4)/(x^(2)-3x+2)=A/(x-2)-B/(x-1) then (A, B) =

Evaluate: lim_(xrarr1) [(x-2)/(x^(2)-x)-(1)/(x^(3)-3x^(2)+2x)]

Simplify: (x^3-2x^2+3x-4)(x-1)-\ (2x-3)(x^2-x+1)

If f(x)=|[x-2, (x-1)^2, x^3] , [(x-1), x^2, (x+1)^3] , [x,(x+1)^2, (x+2)^3]| then coefficient of x in f(x) is

CENGAGE ENGLISH-DETERMINANTS-All Questions
  1. " If " |{:(x^(2)+x,,x+1,,x-2),(2x^(2)+3x-1,,3x,,3x-3),(x^(2)+2x+3,,2x...

    Text Solution

    |

  2. Prove that |cosalpha-cosbeta| le |alpha-beta|

    Text Solution

    |

  3. Statement 1: If b c+q r=c a+r p=a b+p q=-1, t h e n|a p a p b q b q c...

    Text Solution

    |

  4. If f(theta)=|sinthetacosthetasinthetacosthetasinthetacosthetacosthetas...

    Text Solution

    |

  5. If f(theta)=|[sin^2A,cot A,1],[sin^2B,cosB,1],[sin^2C,cosC,1]| , then...

    Text Solution

    |

  6. The roots of the equation |^x Cr^(n-1)Cr^(n-1)C(r-1)^(x+1)Cr^n Cr^n C(...

    Text Solution

    |

  7. Let Delta(x)=|[3,3x,3x^2+2a^2] , [3x, 3x^2+2a^2, 3x^3+6a^2x] , [3x^2+2...

    Text Solution

    |

  8. Consider a system of linear equation in three variables x,y,z a1x+b...

    Text Solution

    |

  9. If f(x)=|[a,-1, 0],[a x, a,-1],[a x^2,a x, a]|,using properties of det...

    Text Solution

    |

  10. If g(x)=(f(x))/((x-a)(x-b)(x-c)),w h e r ef(x) is a polynomial of degr...

    Text Solution

    |

  11. If (x)=|[x^2+4x-3 2x+4 13] [2x^2+5x-9 4x+5 26] [ 8x^2-6x+1 16 x-6 104]...

    Text Solution

    |

  12. If |y z-x^2z x-y^2x y-z^2x z-y^2x y-z^2y z-x^2x y-z^2y z-x^2z x-y^2|=|...

    Text Solution

    |

  13. Let f(n)=|nn+1n+2^n Pn^(n+1)P(n+1)^n Pn^n Cn^(n+1)C(n+1)^(n+2)C(n+2)| ...

    Text Solution

    |

  14. If |[ x^n ,x^(n+2) ,x^(2n)],[1 ,x^a , a ],[x^(n+5),x^(a+6),x^(2n+5)]...

    Text Solution

    |

  15. Let x<1, then value of |[x^2+2, 2x+1 ,1],[ 2x+1,x+2, 1],[ 3, 3 ,1]| is...

    Text Solution

    |

  16. Find the number of real root of the equation |[0,x-a, x-b],[ x+a,0,x-...

    Text Solution

    |

  17. Value of |[x+y, z,z ],[x, y+z, x],[y, y, z+x]|, where x ,y ,z are nonz...

    Text Solution

    |

  18. If e^(itheta)=costheta+isintheta, find the value of |[1,e^(ipi//3),e...

    Text Solution

    |

  19. Which of the following is not the root of the equation |[x,-6,-1],[ 2,...

    Text Solution

    |

  20. If A,B,C are the angles of a non right angled triangle ABC. Then find ...

    Text Solution

    |

  21. Let f(x)=a5x^5+a4x^4+a3x^3+a2x^2+a1x , where ai ' s are real and f(x)=...

    Text Solution

    |