Question 773088
This shape is like a rectangle which is missing an upper-right rectangle piece.  We can find some projected length distances to find the missing rectangle's width and height.


DRAW the figure so you see what my description is.
Let {{{u=(3x-5)-(2x^2+1)}}}  and let {{{v=(2x^2+3)-(x+2)}}}
The area of the missing rectangular piece is {{{u*v}}}.


First find actual u and v in their simplified form; then, find the area of u*v.

{{{u=3x-5-2x^2-1=3x-2x^2-6}}}
and 
{{{v=2x^2+3-x-2=2x^2-x+1}}}

{{{highlight(uv=(-2x^2+3x-6)(2x^2-x+1))}}}


The {{{L + uv = (2x^2+3)(3x-5)}}}
and just the L by itself would be :
The L={{{(2x^2+3)(3x-5)-uv}}}
{{{highlight(L=(2x^2+3)(3x-5)-(-2x^2+3x-6)(2x^2-x+1))}}} square units
.
.
That should simplify to {{{highlight(4x^4-2x^3-3x^2-9)}}}
I just do not get what you report it should be.