Question

9m^3-6m^2n^2+7mn+8 from 3m^3-2mn-5 
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Answer 1

Answer:

$= 3 {m}^{3} - 2mn - 5 - (9 {m}^{3} - 6 {m}^{2} + {n}^{2} + 7mn + 8) \\ \\ = 3 {m}^{3} - 2mn - 5 - 9 {m}^{3} + 6 {m}^{2} - {n}^{2} - 7mn - 8 \\ \\ = 3 {m}^{3} - 9 {m}^{3} + 6 {m}^{2} - {n}^{2} - 2mn - 7mn - 5 - 8 \\ \\ = 6 {m}^{3} + 5 {m}^{2} - {n}^{2} - 9mn - 13$