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If a, b and c are distinct positive real...

If `a, b and c` are distinct positive real numbers such that `Delta_(1) = |(a,b,c),(b,c,a),(c,a,b)|` and `Delta_(2) = |(bc - a^2, ac -b^2, ab - c^2),(ac - b^2, ab - c^2, bc -a^2),(ab -c^2, bc - a^2, ac - b^2)|`, then

A

`Delta_(1) = Delta_(2)`

B

`Delta_(1)^(2) + Delta_(2) = 0`

C

`Delta_(1)^(2) = Delta_(2)`

D

`Delta_(1)^(2) = Delta_(2)^(2)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the determinants \( \Delta_1 \) and \( \Delta_2 \) given in the question. ### Step 1: Calculate \( \Delta_1 \) The determinant \( \Delta_1 \) is given by: \[ \Delta_1 = \begin{vmatrix} a & b & c \\ b & c & a \\ c & a & b \end{vmatrix} \] To compute this determinant, we can use the rule of Sarrus or cofactor expansion. Let's use the cofactor expansion along the first row: \[ \Delta_1 = a \begin{vmatrix} c & a \\ a & b \end{vmatrix} - b \begin{vmatrix} b & a \\ c & b \end{vmatrix} + c \begin{vmatrix} b & c \\ c & a \end{vmatrix} \] Calculating each of these 2x2 determinants: 1. \( \begin{vmatrix} c & a \\ a & b \end{vmatrix} = cb - a^2 \) 2. \( \begin{vmatrix} b & a \\ c & b \end{vmatrix} = bb - ac = b^2 - ac \) 3. \( \begin{vmatrix} b & c \\ c & a \end{vmatrix} = ba - c^2 \) Substituting these back into the expression for \( \Delta_1 \): \[ \Delta_1 = a(cb - a^2) - b(b^2 - ac) + c(ba - c^2) \] ### Step 2: Simplify \( \Delta_1 \) Now, we simplify \( \Delta_1 \): \[ \Delta_1 = acb - a^3 - b^3 + abc + abc - c^3 \] \[ = 3abc - (a^3 + b^3 + c^3) \] ### Step 3: Calculate \( \Delta_2 \) Next, we compute \( \Delta_2 \): \[ \Delta_2 = \begin{vmatrix} bc - a^2 & ac - b^2 & ab - c^2 \\ ac - b^2 & ab - c^2 & bc - a^2 \\ ab - c^2 & bc - a^2 & ac - b^2 \end{vmatrix} \] This determinant can also be computed using cofactor expansion or properties of determinants. ### Step 4: Relate \( \Delta_1 \) and \( \Delta_2 \) From the properties of determinants, specifically the cofactor expansion, we can show that the determinant of the cofactor matrix of \( \Delta_1 \) is equal to \( \Delta_2 \). ### Conclusion After analyzing both determinants, we find that: \[ \Delta_1^2 = \Delta_2 \] Thus, the correct option is: **Option C: \( \Delta_1^2 = \Delta_2 \)**
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