We have,

Let x - 2y = z

Then,

7 (x - 2y)² – 25 (x - 2y) + 12

Now by using middle-term splitting, we get

= 7z² - 25z + 12

= 7z² – 21z - 4z + 12

= 7z (z – 3) - 4 (z – 3)

= (z – 3) (7z - 4)

Now,

Replacing z by (x - 2y), we get

7 (x - 2y)² - 25 (x - 2y) + 12

= (x - 2y – 3) [7 (x - 2y) - 4]

= (x - 2y – 3) (7x - 14y - 4)

Hence,

The given expression can be factorized as: