(х-3у)(3у-х)-(3у-2х)²
помогите пожалуйста

(х-3у)(3у-х)-(3у-2х)²=(-3y+x)(3у-х)-(3у-2х)²=-(3y-x)(3y-x)-(3y-2x)²=-(3y-x)²-(3y-2x)²=-((9y²-6xy+x²)+(9y²-12xy+x²))=-(18y²-18xy+x²)=-18y²+18xy-x²