a. (a−b2)4
=C40a4+C41a3(−b2)+C42a2(−b2)2+C43a(−b2)3+C44(−b2)4
=a4−2a3b+32a2b2−12ab3+116b4
b. (2x2+1)5
=C50(2x2)5+C51(2x2)4.1+C52(2x2)3.12+C53(2x2)2.13+C542x2.14+C55.15
=32x7+80x6+80x6+40x4+10x2+1