\( \left|\begin{array}{ccc}x+1 & 2 & 3 \\ 2 & x+4 & 6 \\ 3 & 6 & x+9\end{array}\right| \) is decressing in.

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khadarabad · Answer 1 · 2024-09-13T19:40:42+0000

x[ (x+2)(x+6) -12 ]+ x[ 6( x+6 ) – 36 ] = x { (x+2)(x+6) - 12 + ( 6( x+6 ) – 36 )} = x { x² + 8x+12 – 12 + 6x + 36 - 36 }

= x { x² + 8x+ 6x } = x³ – 14x

Let f(x) = x³– 14x ,,, Critical points where f(x) slope is zero

Function increasing