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
9.9*9.9+1.99=9.9*9.9+9.9*0.1+1=9.9*(9.9+0.1)+1=99+1=100

=(10-0.1)^2+1.99
=100-2+0.01+1.99
=100

9.9*9.9+1.99
=9.9*9.9+0.99+1
=0.99(10*9.9+1)+1
=0.99*100+1
=99+1
=100

(9.9)的平方+1+0.99
(9.9+1)的平方+0.99
=100