9n^2-4m^2-1+4m因式分解 (>_
问题描述：
9n^2-4m^2-1+4m因式分解 (>_
答
9n²-4m²-1+4m
=9n²-(4m²-4m+1)
=9n²-(2m-1)²
=[3n+(2m-1)][3n-(2m-1)]
=(3n+2m-1)(3n-2m+1)