Given that $x=-9$ is a root of $\left|\begin{array}{lll}x & 3 & 7 \ 2 & x & 2 \ 7 & 6 & x\end{arra

Question

Given that $x=-9$ is a root of $\left|\begin{array}{lll}x & 3 & 7 \ 2 & x & 2 \ 7 & 6 & x\end{array}ight|=0$. Then the sum of the other two roots are

Professor PC Thomas Classes · Answer

$x\left(x^{2}-12ight)-3(2 x-14)+7(12-7 x)=0$ $x^{3}-67 x+126=0 \Rightarrow(x+9)\left(x^{2}-9 x+14ight)=0$ $(x+9)(x-7)(x-2)=0$\ $	herefore \quad x=-9,7,2$\ The other two roots are 2 and 7.\