Previous Year NEET Question- Matrix And Determinant

Q1. The answer is C.

We can expand the determinant by first taking the first row and multiplying the first element by the determinant of the 2x2 matrix formed by the elements in the second and third rows:

$$\begin{vmatrix}1&1&1\x&x^2&x^3\x^2&x^3&x^4\end{vmatrix} = 1\begin{vmatrix}x^2&x^3\x^3&x^4\end{vmatrix} - 1\begin{vmatrix}x&x^2\x^2&x^3\end{vmatrix} + 1\begin{vmatrix}1&1\x^2&x^3\end{vmatrix}$$

$$= 1(x^5 - x^6) - 1(x^3 - x^4) + 1(x^3 - x^4)$$

$$= x^5 - x^6 - x^3 + x^4$$

$$= x^4 - x^3$$

$$= (x-1)(x+1)