1.102×98
= (100+2)(100-2) (平方差公式)
=100^2 - 2^2 = 10000-4 = 9996
2.98²
= (100-2)^2 (完全平方公式)
=100^2 - 2*100*2 + 2^2
=10000-400+4
=9600 + 4=9604