Question

Which will result in a difference of squares?

Answer 1

C

Explanation:

Answer 2

The correct option is 3.

Explanation:

The difference of squares is defined as

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

In option 1,

`(-7x+4)(-7x+4)=(-7x+4)^2`

This expression is a perfect square, therefore this is not the difference of squares. Option 1 is incorrect.

In option 2,

`(-7x+4)(4-7x)=(-7x+4)(-7x+4)=(-7x+4)^2`

This expression is a perfect square, therefore this is not the difference of squares. Option 2 is incorrect.

In option 3,

`(-7x+4)(-7x-4)=(-7x)^2-(4)^2`

This expression is the difference of squares., therefore Option 3 is correct.

In option 4,

`(-7x+4)(7x-4)=-(-7x+4)(-7x+4)=-(-7x+4)^2`

This expression is a perfect square, therefore this is not the difference of squares. Option 4 is incorrect.