Answer:
[tex]\large\boxed{A=9x^2-6xy+y^2}[/tex]
Step-by-step explanation:
The formula of an area of a square:
[tex]A=s^2[/tex]
s - side length
We have s = 3x - y. substitute:
[tex]A=(3x-y)^2[/tex] use (a - b)² = a² - 2ab + b²
[tex]A=(3x)^2-(2)(3x)(y)+y^2=9x^2-6xy+y^2[/tex]
