If a, b, c are unequal,what is the condition | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(A) We are given the determinant $\Delta = \left| \begin{array}{ccc} a & a^2 & a^3 + 1 \ b & b^2 & b^3 + 1 \ c & c^2 & c^3 + 1 \end{array} ight|$.

Vedclass · Accepted Answer

$1 + abc = 0$

Vedclass · Answer

(A) We are given the determinant $\Delta = \left| \begin{array}{ccc} a & a^2 & a^3 + 1 \ b & b^2 & b^3 + 1 \ c & c^2 & c^3 + 1 \end{array} ight|$.By the property of determinants,we can split the third column into two parts:$\Delta = \left| \begin{array}{ccc} a & a^2 & a^3 \ b & b^2 & b^3 \ c & c^2 & c^3 \end{array} ight| + \left| \begin{array}{ccc} a & a^2 & 1 \ b & b^2 & 1 \ c & c^2 & 1 \end{array} ight|$.Taking $abc$ common from the first determinant,we get:$\Delta = abc \left| \begin{array}{ccc} 1 & a & a^2 \ 1 & b & b^2 \ 1 & c & c^2 \end{array} ight| + \left| \begin{array}{ccc} a & a^2 & 1 \ b & b^2 & 1 \ c & c^2 & 1 \end{array} ight|$.In the second determinant,perform column swaps to match the first: $C_3 \leftrightarrow C_2$ then $C_2 \leftrightarrow C_1$. This results in two sign changes,so the sign remains positive:$\Delta = abc \left| \begin{array}{ccc} 1 & a & a^2 \ 1 & b & b^2 \ 1 & c & c^2 \end{array} ight| + \left| \begin{array}{ccc} 1 & a & a^2 \ 1 & b & b^2 \ 1 & c & c^2 \end{array} ight| = (1 + abc) \left| \begin{array}{ccc} 1 & a & a^2 \ 1 & b & b^2 \ 1 & c & c^2 \end{array} ight|$.The value of the determinant $\left| \begin{array}{ccc} 1 & a & a^2 \ 1 & b & b^2 \ 1 & c & c^2 \end{array} ight|$ is $(a - b)(b - c)(c - a)$.Thus,$\Delta = (1 + abc)(a - b)(b - c)(c - a) = 0$.Since $a, b, c$ are unequal,$(a - b)(b - c)(c - a) 
eq 0$.Therefore,the condition is $1 + abc = 0$.

If $a, b, c$ are unequal,what is the condition that the value of the following determinant is zero? $\Delta = \left| \begin{array}{ccc} a & a^2 & a^3 + 1 \\ b & b^2 & b^3 + 1 \\ c & c^2 & c^3 + 1 \end{array} \right|$

Similar Questions

Evaluate $\Delta=\left|\begin{array}{lll}3 & 2 & 3 \\ 2 & 2 & 3 \\ 3 & 2 & 3\end{array}\right|$

The value of $\left| \begin{array}{ccc} 41 & 42 & 43 \\ 44 & 45 & 46 \\ 47 & 48 & 49 \end{array} \right| = $

By using properties of determinants,show that:
$\left|\begin{array}{ccc}0 & a & -b \\ -a & 0 & -c \\ b & c & 0\end{array}\right|=0$

If $\left| \begin{array}{ccc} a & b & c \\ m & n & p \\ x & y & z \end{array} \right| = k$,then $\left| \begin{array}{ccc} 6a & 2b & 2c \\ 3m & n & p \\ 3x & y & z \end{array} \right| = $

The determinant $\left| \begin{array}{ccc} 1 & 1 & 1 \\ 1 & 2 & 3 \\ 1 & 3 & 6 \end{array} \right|$ is not equal to

Vedclass Test Series

Exam Paper Generator

Online Exam Module