If 3cot A= 4 check whether 1-tan'2A/1+tan'2A =cos'2 A - sin'2 A or not​

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