(1)10^7÷(10^3÷10^2)
=10^7/10^3*10^2
=10^(7-3+2)
=10^6
(2)[(3a+b)^2-b^2]÷a
=(9a^2+6ab+b^2-b^2)/a
=9a+6b
运用整式乘法公式进行计算
(3)899×901+1
=(900-1)(900-1)+1
=900^2
=8100
(4)123^2-124×122
=123^2-(123+1)(123-1)
=123^2-123^2+1
=1