If the dimensions of a rectangle are a plus 3b and a minus 3b what is the area of the rectangle

area=legnth times width

we notice this is a special case

(a+b)(a-b)=a^2-b^2

area=(a+3b)(a-3b)=a^2-9b^2

area=a^2-9b^2

i think asking google will you get the answer to that question