9.9*9.9+1.99简便运算
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9.9*9.9+1.99简便运算9.9*9.9+1.99简便运算9.9*9.9+1.99简便运算=(10-0.1)*9.9+1.99=99-0.99+1.99=1009.9*9.9+1.99=(1-0
9.9*9.9+1.99简便运算
9.9*9.9+1.99简便运算
9.9*9.9+1.99简便运算
=(10-0.1)*9.9+1.99
=99-0.99+1.99
=100
9.9*9.9+1.99
=(1-0.1)^2+1.99
=1^2-2*1*0.1+0.1^2+1.99
=1-0.2+0.01+1.99
=0.8+2
=2.8
100
9.9*9.9+1.99 = 9.9*9.9 + 2*9.9*0.1 + 0.1*0.1 = (9.9 + 0.1)*(9.9 + 0.1) = 10*10 = 100