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What is |{:(-a^(2),ab,ac),(ab,-b^(2),bc)...

What is `|{:(-a^(2),ab,ac),(ab,-b^(2),bc),(ac,bc,-c^(2)):}|` equal to ?

A

`4a^(2) b^(2)`

B

`4b^(2) c^(2)`

C

`4c^(2) a^(2)`

D

`4a^(2) b^(2) c^(2)`

Text Solution

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The correct Answer is:
To find the value of the determinant \[ D = \begin{vmatrix} -a^2 & ab & ac \\ ab & -b^2 & bc \\ ac & bc & -c^2 \end{vmatrix} \] we will follow these steps: ### Step 1: Factor out common terms from the columns We can factor out \(-a\) from the first column, \(b\) from the second column, and \(c\) from the third column. \[ D = (-a)(b)(c) \begin{vmatrix} a & b & c \\ b & -b & \frac{bc}{b} \\ c & \frac{bc}{c} & -c \end{vmatrix} \] This simplifies to: \[ D = -abc \begin{vmatrix} a & b & c \\ b & -b & c \\ c & b & -c \end{vmatrix} \] ### Step 2: Rewrite the determinant Now we can rewrite the determinant: \[ D = -abc \begin{vmatrix} a & b & c \\ b & -b & c \\ c & b & -c \end{vmatrix} \] ### Step 3: Expand the determinant We will expand the determinant along the first row: \[ D = -abc \left( a \begin{vmatrix} -b & c \\ b & -c \end{vmatrix} - b \begin{vmatrix} b & c \\ c & -c \end{vmatrix} + c \begin{vmatrix} b & -b \\ c & b \end{vmatrix} \right) \] ### Step 4: Calculate the 2x2 determinants Calculating the 2x2 determinants: 1. \(\begin{vmatrix} -b & c \\ b & -c \end{vmatrix} = (-b)(-c) - (c)(b) = bc - bc = 0\) 2. \(\begin{vmatrix} b & c \\ c & -c \end{vmatrix} = (b)(-c) - (c)(c) = -bc - c^2 = -bc - c^2\) 3. \(\begin{vmatrix} b & -b \\ c & b \end{vmatrix} = (b)(b) - (-b)(c) = b^2 + bc\) ### Step 5: Substitute back into the determinant Substituting these values back into the determinant: \[ D = -abc \left( a(0) - b(-bc - c^2) + c(b^2 + bc) \right) \] This simplifies to: \[ D = -abc \left( b(bc + c^2) + c(b^2 + bc) \right) \] ### Step 6: Simplify the expression Now we can simplify the expression: \[ D = -abc \left( b^2c + bc^2 + cb^2 + c^2b \right) = -abc(2b^2c + 2bc^2) \] ### Step 7: Final expression Thus, we have: \[ D = -2abc(b^2 + c^2) \] ### Final Result The value of the determinant is: \[ D = -abc(a^2 + b^2 + c^2) \]

To find the value of the determinant \[ D = \begin{vmatrix} -a^2 & ab & ac \\ ab & -b^2 & bc \\ ac & bc & -c^2 \end{vmatrix} ...
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OBJECTIVE RD SHARMA ENGLISH-DETERMINANTS-Chapter Test
  1. What is |{:(-a^(2),ab,ac),(ab,-b^(2),bc),(ac,bc,-c^(2)):}| equal to ?

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  2. STATEMENT-1: The lines a(1)x+b(1)y+c(1)=0a(2)x+b(2)y+c(2)=0,a(3)x+b(3)...

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  3. If D =|{:(1,1,1),(1,1+x,1),(1,1,1+y):}|"for" " "xne0,yne0 then D is

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  4. Use properties of determinants to solve for x: |{:(,x+a,b,c),(,c,x+b,a...

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  5. |(sin^(2) x,cos^(2) x,1),(cos^(2) x,sin^(2) x,1),(- 10,12,2)| =

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  6. The system of linear equations x + y + z = 2 2x + y -z = 3 3x + ...

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  7. The roots of the equation |(3x^(2),x^(2) + x cos theta + cos^(2) the...

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  8. |(bc,bc'+b'c,b'c'),(ca,ca'+c'a,c'a'),(ab,ab'+a'b,a'b')| is equal to

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  9. If alpha, beta, gamma are the cube roots of 8 , then |(alpha,beta,gamm...

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  10. One root of the equation |(3x-8, 3, 3),(3,3x-8, 3),(3,3,3x-8)|=0 is ...

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  11. If a,b and c are non- zero real number then prove that |{:(b^(2...

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  12. If x, y , z are in A.P., then the value of the det (A) is , where A ...

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  13. The value of |(b +c,a,a),(b,c +a,b),(c,c,a +b)|, is

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  14. If a ,\ b ,\ c are non-zero real numbers and if the system of equat...

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  15. If a!=6,b,c satisfy|[a,2b,2c],[3,b,c],[4,a,b]|=0 ,then abc =

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  16. The value of Delta = |(1^(2),2^(2),3^(2)),(2^(2),3^(2),4^(2)),(3^(2),4...

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  17. Prove: |a a+b a+2b a+2b a a+b a+b a+2b a|=9(a+b)b^2

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  18. If all the elements in a square matrix A of order 3 are equal to 1 or ...

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  19. Sum of real roots of the euation |{:(1,4,20),(1,-2,5),(1,2x,5x^(2)):}|...

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  20. If f(x)=|{:(sinx,cosx,tanx),(x^(3),x^(2),x),(2x,1,x):}|, then lim(xto0...

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  21. If A, B and C are the angles of a triangle and |(1,1,1),(1 + sin A,1...

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