We are given the result of adding two polynomials is:
One of the polynomials that is added is:
To determine the polynomial that was added we will use a polynomial with the same variables that appear on each polynomial but with unknown coefficients, like this:
Now we associate like terms:
Now, each of the new coefficients must be equal to the coefficients in the resulting polynomial, therefore, we have for the first term:
For the second term:
For the third term:
For the fourth term:
For the last term:
Now that we have the coefficients we can substitute in the polynomial we added, we get: