Question

Помогите номер 35.15 ДАМ Много балов

Answer 1

Ответ:

$1)\ \ (5z^2-6k)^2-(5z^2+3k)^2+90z^2k=\\\\=25z^4-60z^2k+36k^2-(25z^4+30z^2k+9k^2)+90z^2k=36k^2-9k^2=27k^2\\\\27k^2=27k^2\\\\2)\ \ (m^2-n^2)(m^2+n^2)-m^2\, (m^2-n^2)-m^2n^2=\\\\=m^4-n^4-m^4+m^2n^2-m^2n^2=-n^4\\\\-n^4=-n^4\\\\3)\ \ (1,2x^4-7y^2)(1,2x^4+7y^2)+0,56x^8+49y^4=\\\\=1,44x^8-49y^4+0,56x^8+49y^4=2x^8\\\\2x^8=2x^8\\\\4)\ \ (1,4a^3-5b^2)(1,4a^3+5b^2)-2,96a^6+25b^4=\\\\=1,96a^6-25b^4-2,96a^6+25b^4=-a^6\\\\-a^6=-a^6$