Question

(5n2 – 4nm - 9m²) + (7n2 + 4nm +8m²) =

Answer 1

`\left(5n^2-4nm-9m^2\right)+\left(7n^2+4nm+8m^2\right)=12n^2-m^2`

Explanation:

Given the expression

`\left(5n^2\:-\:4nm\:-\:9m^2\right)\:+\:\left(7n^2\:+\:4nm\:+8m^2\right)`

Remove parentheses: (a) = a

`=5n^2-4nm-9m^2+7n^2+4nm+8m^2`

Group like terms

`=5n^2+7n^2-4nm+4nm-9m^2+8m^2`

Add similar elements:
`5n^2+7n^2=12n^2`

`=12n^2-4nm+4nm-9m^2+8m^2`

Add similar elements:
`-4nm+4nm=0`

`=12n^2-9m^2+8m^2`

Add similar elements:
`-9m^2+8m^2=-m^2`

`=12n^2-m^2`

Therefore, we conclude that:

`\left(5n^2-4nm-9m^2\right)+\left(7n^2+4nm+8m^2\right)=12n^2-m^2`