Respuesta :

The polynomial to be added to –7mn + 2m² + 3n² to obtain 5m² + 2mn - 9n² is: 3m² - 11n² + 9mn.

Addition of Polynomials

Like terms should be combined together when adding polynomials.

Let x represent the polynomial expression that would be added to –7mn + 2m² + 3n² to obtain 5m² + 2mn - 9n².

Therefore:

–7mn + 2m² + 3n² + x = 5m² + 2mn - 9n².

x = 5m² + 2mn - 9n² - (-7mn + 2m² + 3n²)

x = 5m² + 2mn - 9n² + 7mn - 2m² - 3n²

Combine like terms together.

x = 3m² - 11n² + 9mn

Therefore, the polynomial to be added to –7mn + 2m² + 3n² to obtain 5m² + 2mn - 9n² is: 3m² - 11n² + 9mn.

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