Answer
$(x-3y)(x-8y)$
Work Step by Step
The 2 numbers whose product is $ac=
1(24)=24
$ and whose sum is $b=
-11
$ are $\left\{
-3,-8
\right\}.$ Using these two numbers to decompose the middle term of the given trinomial, $
x^2-11xy+24y^2
,$ then the factored form is
\begin{array}{l}
x^2-3xy-8xy+24y^2
\\\\=
(x^2-3xy)-(8xy-24y^2)
\\\\=
x(x-3y)-8y(x-3y)
\\\\=
(x-3y)(x-8y)
.\end{array}