Answer:
Difference of squares
Explanation:
y^2-81w^2 is in a special form, as given. Let's find out what form it is:
Let's use a^2-b^2 as an example.
Both of these numbers are square numbers, because they can be represented as a number multiplied by itself
a^2=a*a
b^2=b*b
But what happens when you subtract these squares?
Well, this is a rule with polynomials and binomials (commonly binomials) known as the difference of squares, where two square numbers are subtracted.
This can be proven with numbers.
a^2-b^2=(a-b)(a+b)
13^2-9^2=(13+9)(13-9)=22*4=88
The difference of squares can be represented as the product of the sum and the difference of the numbers that are squared.
y^2-81w^2=(y-9w)(y+9w)
This form is the difference of squares.