Question

Which expressions are differences of squares?

Choose all answers that are correct.

8b^2 - 16c^6

16e^8 - 81g^4

49x^25 - 4y16

121m^18 - 9n^10

Answer 1

16e^8-81g^4 and 121m^18-9n^10

Answer 2

• 16e^8 - 81g^4
• 121m^18 - 9n^10

Explanation:

For a term to be a square, the coefficient must be a square (8 is not), and the degree must be even (25 is not). Of course, the sign between the terms must be a minus sign.

After eliminating the expressions that don't contain squares, the remaining expressions are listed above.