[tex]4m^6 - 16m^{10} [/tex]
[tex]= (2m^3)^2 - (4p^5)^2[/tex]
[tex] = (2m^3 -4p^5)(2m^3 + 4p^5)[/tex]
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This expression is the difference of 2 squares :
[tex]\bf 9n^4 - 49n^6[/tex]
[tex]= (3n^2)^2 - (7n^4)^2[/tex]
[tex]= (3n^2 + 7n^4) (3n^2 - 7n^4)[/tex]