А) x^{2} +2xy+ y^{2}- z^{2}
б) x^{2} -2xy+ y^{2}- z^{2}
в) m^{2} - n^{2} +2nk+ k^{2}
г) m^{2} - n^{2} -2nk+ k^{2}
д) a^{2} +8a+16-16
е)100-100-20n+ n^{2}
ж)81-4 b^{2} +24b+36
з)144-72x+9 x^{2} -16
и)64 x^{2} +4x+1- \frac{4}{9}
к) x^{2} +xy+y^{2}- x^{2} -xy+ y^{2}
л)4 m^{2}-4mn+ n^{2}-m+2 n^{2}
м)9 n^{2}+6np+4 p^{2}-25p^{2}-10pn+4n^{2}
н)3600 a^{2}+1800ab+900b^{2}-729a^{2}+486ab+324b^{2}
o) 1225 x^{4}+1960 x^{2}+3136-144 x^{2}-36