Answer:
x² + 23x + 49
Explanation:
The area of the shaded region = area of outer rectangle - area of white square.
A = (x + 10)(2x + 5) - (x + 1)(x + 1) ← expand factors using FOIL
= 2x² + 25x + 50 - (x² + 2x + 1)
= 2x² + 25x + 50 - x² - 2x - 1 ← collect like terms
= x² + 23x + 49