Answer:
[tex]A=x^2+12x+27\ units^2[/tex]
Step-by-step explanation:
we know that
The area of the model is equal to the area of a rectangle
The area of a rectangle is equal to
[tex]A=LW[/tex]
we have
[tex]L=x+9\ units[/tex]
[tex]W=x+3\ units[/tex]
substitute
[tex]A=(x+9)(x+3)[/tex]
Apply distributive property
[tex]A=x^2+3x+9x+27[/tex]
Combine like terms
[tex]A=x^2+12x+27\ units^2[/tex]
