The sum of the polynomials is;
[tex]15x^2-5x[/tex]Here, we want to add the given polynomials
We can do this by adding the similar terms together;
[tex]\begin{gathered} (9x^2-4x)+(6x^2-x) \\ 9x^2-4x+6x^2_{}-x \\ 9x^2+6x^2-4x-x \\ 15x^2-5x \end{gathered}[/tex]