Answer: [tex]y^2-100.[/tex]
Step-by-step explanation:
if we have a square with sides 'y' units,
then, its breadth = length = y
If we add 10 to one side it will become (y+10) (longer one) and subtract 10 from another, then it will become (y-10) (shorter one).
Area of rectangle = breadth x length
So, area of rectangle [tex]= (y+10)(y-10)[/tex]
[tex]= y^2-10^2=y^2-100\ \ \ \ \ [(a-b)(a+b)=a^2-b^2][/tex]
Hence, the new area as a polynomial = [tex]y^2-100.[/tex]
