Hello!
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To add polynomials, combine like terms. Don't add exponents.
[tex](2mn + 4n^{2} ) + (5 {m}^{2} - 7mn)[/tex]
Remove the parenthesis and combine like terms.
[tex]4n^{2} + 5 {m}^{2} - 5mn[/tex]
Rewrite in Standard Form:
[tex]5m^{2} - 5mn + 4 {n}^{2} [/tex]
So the answer is C.
