You are to invent x^2, x and constant terms that sum up to specified figures.
You could begin with 6x^2-8x^2, which sums up to -2x^2.
Next, try 7x-4x, which subtract to 3x.
Last, choose two constants that sum up to 3.
Your poly? 6x^2 - *x^2 + 7x - 4x + ? + ?