How do I factor this completely? 4r^2 + 1 -4r ?

4r² + 1 - 4r rearrange into:

4r² - 4r + 1
= 4r² - 4r + 1
= 4r² - 2r - 2r + 1 factor by grouping
= (4r² - 2r) - (2r + 1)
= (2r - 1)(2r - 1) same factors, so
= (2r - 1)²

(2r-1)^2

4r^2 + 1 - 4r
= 4r^2 - 4r + 1
= 4r^2 - 2r - 2r + 1
= (4r^2 - 2r) - (2r - 1)
= 2r(2r - 1) - 1(2r - 1)
= (2r - 1)(2r - 1)

4r² + 1 - 4r
= 4r² - 4r + 1
= (2r - 1)(2r - 1)
= (2r - 1)²

Done

(2r-1)^2

first change the order so it in decreasing order... 4r^2-4r+1=(2r-1)(2r-1) so (2r-1)^2

(2r - 1)^2

r+4 and r-1