Question

Which expression is a difference of squares?

Answer 1

The answer is
$9 {m}^{4} - 49 {n}^{6}$
In the choices; the coefficients 21, 32 and 10 are not perfect squares.

Answer 2

Answer:

Option A is the correct answer.

Step-by-step explanation:

Which expression is a difference of squares?

$9m^{4}-49n^{6}$

Here both 9 and 49 are perfect squares.

9 is the perfect square of 3 and 49 is the perfect square of 7.

In rest options, one term is a perfect square and one is not. Like in 2nd option, 16 is square of 4 but 21 is of none. Similarly in option 4th, 100 is a square of 10 but 10 is of none.

So, option A is the correct answer.