The polynomial which must be added to 3x² +4x + 7 to obtain a sum of 0 is; -3x² -4x +7.
Let the polynomial which must be added to 3x² +4x + 7 to obtain a sum of 0 be represented by P.
In essence;
By subtracting 3x² +4x + 7 from both sides of the equation to obtain the value of P; we have;
Ultimately, P = -3x² -4x +7.
Read more on polynomials;
https://brainly.com/question/2833285