Help pleasenfnekkdkd

1. what are the missing reasons in the proof 2. it's in the second picture and 3

Alina fully simplifies this polynomial and then writes it in standard form. xy2 – 2x2y + 3y3 – 6x2y + 4xy2 if alina wrote the last term as 3y3, which must be the first term of her polynomial in standard form? xy2 5xy2 –8x2y –2x2y

Factor the polynomial expression x6 – x3 – 20