Let $\begin{vmatrix}x & 2 & x \\x^2 & x & 6 \\x & x & 6 \end{vmatrix}= ax^4 +bx^3 +cx^2 +dx+e$ Then, the value of $5a+4b +3c +2d+ e$ is equal to |
-11 -10 -13 -14 |
-11 |
The correct answer is option (1) : -11 We have, $\begin{vmatrix}x & 2 & x \\x^2 & x & 6 \\x & x & 6 \end{vmatrix}$ $= \begin{vmatrix}x & 2 & x \\x^2 & x & 6 \\x-x^2 & 0 & 0 \end{vmatrix}$ [Applying $R_3→ R_3- R_2 $] $=(x-x^2)(12-x^2)$ $= 12x-x^3-12x^2 +x^4 $ $∴a=1, b=-1, c=-12, d= 12 $ and $e= 0 $ $∴5a+4b + 3c + 2d + e= 5-4 - 36 + 24 +0 = -11 $ |