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If Delta1=|(x,a,b),(b,x,a),(a,b,x)| and ...

If `Delta_1=|(x,a,b),(b,x,a),(a,b,x)| and Delta_2=|(x,b),(a,x)|` are the given determinants then

A

`Delta_1=3(Delta_2)^2`

B

`(d/(dx))(Delta_1)=3Delta_2`

C

`(d/(dx))(Delta_1)=3(Delta_2)_2`

D

`Delta_1=3(Delta_2)^(3/2)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to calculate the determinants \( \Delta_1 \) and \( \Delta_2 \) and then analyze the relationship between them. ### Step 1: Calculate \( \Delta_1 \) Given: \[ \Delta_1 = \begin{vmatrix} x & a & b \\ b & x & a \\ a & b & x \end{vmatrix} \] To calculate this determinant, we can use the method of cofactor expansion along the first row. \[ \Delta_1 = x \begin{vmatrix} x & a \\ b & x \end{vmatrix} - a \begin{vmatrix} b & a \\ a & x \end{vmatrix} + b \begin{vmatrix} b & x \\ a & b \end{vmatrix} \] Calculating the 2x2 determinants: 1. \( \begin{vmatrix} x & a \\ b & x \end{vmatrix} = x^2 - ab \) 2. \( \begin{vmatrix} b & a \\ a & x \end{vmatrix} = bx - a^2 \) 3. \( \begin{vmatrix} b & x \\ a & b \end{vmatrix} = bb - ax = b^2 - ax \) Substituting these back into the expression for \( \Delta_1 \): \[ \Delta_1 = x(x^2 - ab) - a(bx - a^2) + b(b^2 - ax) \] Expanding this: \[ = x^3 - abx - abx + a^3 + b^3 - abx \] Combining like terms gives: \[ \Delta_1 = x^3 + a^3 + b^3 - 3abx \] ### Step 2: Calculate \( \Delta_2 \) Given: \[ \Delta_2 = \begin{vmatrix} x & b \\ a & x \end{vmatrix} \] Calculating this determinant: \[ \Delta_2 = x^2 - ab \] ### Step 3: Analyze the relationship between \( \Delta_1 \) and \( \Delta_2 \) We need to find the derivative of \( \Delta_1 \) with respect to \( x \): \[ \frac{d}{dx} \Delta_1 = \frac{d}{dx}(x^3 + a^3 + b^3 - 3abx) \] Calculating the derivative: \[ = 3x^2 - 3ab \] Now, we calculate \( 3 \Delta_2 \): \[ 3 \Delta_2 = 3(x^2 - ab) = 3x^2 - 3ab \] ### Conclusion From the calculations, we see that: \[ \frac{d}{dx} \Delta_1 = 3 \Delta_2 \] Thus, the correct option is that the derivative of \( \Delta_1 \) with respect to \( x \) is equal to 3 times \( \Delta_2 \).
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