How do i factor this36(2x-y)^2-25(u-2y)^2

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how do i factor this
36(2x-y)^2-25(u-2y)^2

i was thinking to expand the brackets first?? but I am not really sure
 
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In general the difference of two squares (which is what you have) is easily factored.

a^2-b^2=(a+b)(a-b)
 
alright so once I've got that what do i do with the 25 and 36 outside the brackets
 
Once you 'do that' you don't have any 25 or 36 outside any brackets.
 
5^2 = 25
6^2 = 36
 
Let 2x-y=A and u=2y=B

36(A^2) - 25(B^2)= (6A)^2 - (5B)^2
 
Since we know 6^2 = 36 could you do it easier if it was written as: 36(2x-y)^2 = 6^2(2x-y)^2 = [(6)(2x-y)]^2 and you did the same process to simplify the other term.