初中阶段,我们学过的三种非负数:绝对值、偶次方(主要是平方)、算术根(主要是算术平方根)。关于非负数,有一个非常重要而简单的结论:有限个非负数的和为0,则必然有这些数均为0。这一性质,在中考和竞赛中倍受关注.应作为基本功加以训练.这里举一些典型例子供参考,望达举一反三之目的. In junior high school, we learned three kinds of non-negative numbers: absolute value, even-order square (mainly square), and arithmetic root (mainly arithmetic square root). With regard to non-negative numbers, there is a very important and simple conclusion: if the sum of a finite number of non-negative numbers is 0, then there must be a zero for these numbers. This nature has attracted much attention in the examinations and competitions. It should be used as a basic skill training. Here are some typical examples for reference, hope to achieve the purpose of inference.