Using the identity :
(a+b)2=a2+2ab+b2
(i)(m2−n2m)2+2m3n2
=(m2)2+(n2m)2−2(m2)(n2m)+2m3n2
=m4+n4m2−2(m)3n2+2m3n2
=m4+n4m2
=(5)4+(10)4(5)2
=625+250000
=250625
(ii) (7m−8n)2+(7m+8n)2
=(7m)2+(8n)2−2(7m)(8n)+(7m)2+(8n)2+2(7m)(8n)
=49m2+64n2+49m2+64n2
=98m2+128n2
=98(5)2+128(10)2
=2450+12800
=15250