Respuesta :

(x⁷ + 5x⁴ - x + 2) - (5x⁴ - x³ + 2) =
x⁷ + 5x⁴ - x + 2 - 5x⁴ + x³ - 2 =
x⁷ + x³ - x 
(x^7+5x^4-x+2)-(5x^4-x^3+2)
=x^7+5x^4-x+2-5x^4+x^3-2
Combining like terms
x^7+5x^4-5x^4+x^3-x+2-2
=x^7+x^3-x is your final answer. Hope it help!