Step-by-step explanation:
first
(0.8a+0.4b)^2= (0.8a+0.4b) *(0.8a+0.4b)
=
0.64 a^2 + 0.32 ab +0.32ab + 0.16 b^2=
0.64 a^2 + 0.64ab + 0.16 b^2
second
(0.8a-0.4b)^2+1.28ab
= 0.64 a^2 - 0.64ab +0.16 b^2 + 1.28ab
= 0.64 a^2 + 0.64ab + 0.16 b^2
since the first (left parameters ) equals the second(right side parameters)
approved✓✓
