Answer:
3[a + b][a - b]
Step-by-step explanation:
Let us recall a useful formula. This formula can factorize any subtraction between perfect squares. The formula is known as a² - b² = (a - b)(a + b).
Let's apply the formula in the given expression as we can see that two perfect squares are being subtracted from each other. Then, we get:

![\implies [(2a - b) - (a - 2b)][(2a - b) + (a - 2b)]](https://tex.z-dn.net/?f=%5Cimplies%20%5B%282a%20-%20b%29%20-%20%28a%20-%202b%29%5D%5B%282a%20-%20b%29%20%2B%20%28a%20-%202b%29%5D)
Since the expression(s) inside the parentheses ( ) cannot be simplified further, we can open the parentheses ( ). Then, we get:
![\implies [(2a - b) - (a - 2b)][(2a - b) + (a - 2b)]](https://tex.z-dn.net/?f=%5Cimplies%20%5B%282a%20-%20b%29%20-%20%28a%20-%202b%29%5D%5B%282a%20-%20b%29%20%2B%20%28a%20-%202b%29%5D)
![\implies [2a - b - a + 2b][2a - b + a - 2b]](https://tex.z-dn.net/?f=%5Cimplies%20%5B2a%20-%20b%20-%20a%20%2B%202b%5D%5B2a%20-%20b%20%2B%20a%20-%202b%5D)
Now, we can combine like terms and simplify:
![\implies [2a - b - a + 2b][2a - b + a - 2b]](https://tex.z-dn.net/?f=%5Cimplies%20%5B2a%20-%20b%20-%20a%20%2B%202b%5D%5B2a%20-%20b%20%2B%20a%20-%202b%5D)
![\implies [a + b][3a - 3b]](https://tex.z-dn.net/?f=%5Cimplies%20%5Ba%20%2B%20b%5D%5B3a%20-%203b%5D)
Three is common in 3a - 3b. Thus, we can factor 3 out of the expression:
![\implies [a + b][3a - 3b]](https://tex.z-dn.net/?f=%5Cimplies%20%5Ba%20%2B%20b%5D%5B3a%20-%203b%5D)
![\implies [a + b] \times [3a - 3b]](https://tex.z-dn.net/?f=%5Cimplies%20%5Ba%20%2B%20b%5D%20%5Ctimes%20%5B3a%20-%203b%5D)
![\implies [a + b] \times 3[a - b]](https://tex.z-dn.net/?f=%5Cimplies%20%5Ba%20%2B%20b%5D%20%5Ctimes%203%5Ba%20-%20b%5D)
![\implies \boxed{3[a + b][a - b]}](https://tex.z-dn.net/?f=%5Cimplies%20%5Cboxed%7B3%5Ba%20%2B%20b%5D%5Ba%20-%20b%5D%7D)
Therefore, 3[a + b][a - b] is the factorized expression of (2a - b)² - (a - 2b)².
Learn more about factoring expressions: brainly.com/question/1599970