4m2-25n2 +6m-15n?

4m^2－25n^2 +6m－15n
=(4m^2+6m+2.25)－(25n^2+15n+2.25)
=(2m+1.5)^2－(5n+1.5)^2
=(2m+1.5－5n－1.5)(2m+1.5+5n+1.5)
=(2m－5n)(2m+5n+3)
Hint：6^2/(4*4)=2.25

4m^2-25n^2 +6m-15n
=(2m-5n)(2m+5n)+3(2m-5n)
=(2m-5n)(2m+5n+3)