Final answer:
To find the expression that shows how much grain the silo can hold, expand the square and multiply it by the height.
Step-by-step explanation:
To find the expression that shows how much grain the silo can hold, we need to expand the square in the expression (2x9)^2 and then multiply it by the height, 10x10.
Expanding the square, we get (2x9)^2 = 4x9^2 = 4x81 = 324.
Multiplying the expanded square by the height, we get 324x10x10 = 32,400x.
Therefore, the expression that shows how much grain the silo can hold is 32,400x.