我们知道在实数的加法运算中,任何一个实数加0都等于这个实数本身,因此好像0是一个可有可无的数,那么0是否真的可有可无呢?它到底有哪些作用呢?在数轴上原点所表示的数是0,它左面的点表示的是负数,它右面的点表示的是正数.一个数从x_1变化到x_2,若x_2-x_1>0则表示增加了;若x_2-x_1<0,则表示减少了;若x_2-x_1=0,则表示没有变化。因此0是正、负数的界 We know that any real number plus 0 equals the real number itself in addition to real numbers, so it seems that 0 is a negligible number, so is 0 really dispensable? What exactly does it do? On the axis, the number represented by the origin is 0, the point on the left shows a negative number, and the point on the right shows a positive number. A number changes from x_1 to x_2, while x_2-x_1> 0 means an increase. -x_1 <0, then reduced; if x_2-x_1 = 0, then there is no change. So 0 is positive, negative bound