(5х-у2)(5х-у2)-2(15х-7у2)-40

(5х-у²)(5х-у²)-2(15х-7у²)-40=25х²-у⁴-30х-14у-40=(25х²-30х)-(у⁴-14у)-40=((5х)²-2·5х·3+3²)-9-((у²)²-2·у²·7·7²)-49=(5х-3)²(у²-7)²=(5х-3+у²-7)(5х-3-у²+7)=(5х-10+у²)(5х+4-у²).