Transform the given system

$x_1^{\text{'}}=2x_1-8x_2$

$x_2^{\text{'}}=11x_1-5x_2$

into a single differential equation of second$-$order for $x_1.$

$x_1^{\text{'}\text{'}}7x_1^{\text{'}}21x_1=0$

$x_1^{\text{'}\text{'}}3x_1^{\text{'}}78x_1=0$

$x_1^{\text{'}\text{'}}7x_1^{\text{'}}78x_1=0$

$x_1^{\text{'}\text{'}}3x_1^{\text{'}}21x_1=0$

$x_1^{\text{'}\text{'}}-2x_1^{\text{'}}-10x_1=0$