Question

Which products result in a difference of squares? Check all that apply. (5z + 3)(–5z – 3) (w – 2.5)(w + 2.5) (8g + 1)(8g + 1) (–4v – 9)(–4v + 9) (6y + 7)(7y – 6) (p – 5)(p – 5)

Answer 1

Answer:

Option 2  $(w-2.5)(w+2.5)=w^2-2.5^2$ and option 4 $(-4v-9)(-4v+9)=-(4v+9)(-)(4v-9)=4v^2-9^2$

Explanation:

In option 1 $(5z+3)(-5z-3)=-(5z+3)(5z+3)=-(5z+3)^2$  which is not the difference of squares

In option 2 $(w-2.5)(w+2.5)=w^2-2.5^2$ using the formula

$(a+b)(a-b)=a^2-b^2\\Here \\a=w,b=2.5$

Clearly, the difference of squares

In option 3$(8g+1)(8g+1)=(8g+1)^2$ not the difference of squares

In option 4$(-4v-9)(-4v+9)=-(4v+9)(-)(4v-9)=4v^2-9^2$

Clearly the difference of squares

In option 5 $(6y+7)(7y-6)=42y^2+13y-42$ not the difference of squares

In option 6 $(p-5)(p-5)=(p-5)^2$ not the difference of squares

Answer 2

these are the answers because i had the same question and they told me these were the answers 
(w – 2.5)(w + 2.5)

(–4v – 9)(–4v + 9)