Question

Which expressions are differences of squares?

Choose all answers that are correct.

t^2 - 1

n^2 - 225

k^2 + 81

p^2 - 40

Answer 1

• t^2 - 1
• n^2 - 225

Explanation:

For an expression to be a difference of squares, it must be a difference of two terms, each of which is a square. A term is a square if its coefficient is a square and if its degree is even.

The third expression is a sum, not a difference; the fourth expression has a term that is not a square (40). Neither of those is a difference of squares.