Hello from MrBillDoesMath!
Answer:
x^2 + 23 x + 49
Discussion:
Area of Shaded region =
Area of Full rectangle - Area of small rectangle =
(2x+5)(x+10) - (x+1)^2 =
( 2x*x + 2x*10 * 5*x + 5*10) - (x^2 + 2x + 1) =
(2x^2+25x+50) - (x^2 +2x + 1) =
(2x^2 - x^2) + (25x -2x) + (50-1) =
x^2 + 23 x + 49
Thank you,
MrB