Answer :
Answer:
The given expression in descending powers of m is
[tex]{\bf 3m^3+3m^2n-7m^2n-n^3}[/tex]
Step-by-step explanation:
The given expression is [tex](5m^3+3mn^2)+(-7m^2n+mn^2-n^3)-(mn^2+2m^3)[/tex]
Now solve the above expression
[tex](5m^3+3mn^2)+(-7m^2n+mn^2-n^3)-(mn^2+2m^3)=5m^3+3mn^2-7m^2n+mn^2-n^3-mn^2-2m^3 [/tex]
[tex](5m^3+3mn^2)+(-7m^2n+mn^2-n^3)-(mn^2+2m^3) = 3m^3+3m^2n-7m^2n-n^3[/tex] (where [tex]mn^2[/tex] and [tex]-mn^2[/tex] getting cancelled because of alternate signs)
Therefore the above expression in descending powers of m is
[tex]3m^3+3m^2n-7m^2n-n^3[/tex]