Respuesta :

1. -5x^10, because 4-9 is 5 and you don't do anything do the exponents when subtracting.
2. 9x^2-12x-6, quadratic trinomial
3. 5.5x^2+5.5x^2-9.2x+9.9x+9.6+1.3=

11x^2+0.7x+8.2