正数和零统称为非负数,初中数学中的非负数常以下面三种形式出现:(1)以绝对值的形式出现,即无论a为任何实数,总有|a|≥0;(2)以平方的形式出现,即无论a是任何实数,总有a2≥0; Positive and zero are collectively referred to as non-negative, non-negative mathematics in junior high school often appear in the following three forms: (1) in the form of absolute value, that is, no matter a is any real, always | a | ≥0; ) Appears in the form of a square, that is, no matter a is any real number, there is always a2≥0;