Question

49x^2 - 4y^2

Answer 1

we can see that both numbers of 49 and 4 are perfect squares so we can square them and do this.
(7x)^2 - (2y)^2
now you can use the difference of two squares.

Answer 2

difference of two squares:
\(a^2 - b^2 = (a+b)(a-b)\)
Now, match a and b with the question.