“不是正数则必定是负数。”“绝对值总归是正的。”“x~2总大于零。”“求函数定义域时要根号内为正数。”“方程ax~2+bx+c=0有实根,则判别式△≥0。”“要使一元二次不等式ax~2+bx+c>0对于任何实数x恒成立,则判别式△<0。“a的零次幂为1”“R=R~+∪R~-”其中R表示实数集合,而R~+与R~-分别表示正数集合与负数集合。 “If it is not a positive number, it must be a negative number.” “The absolute value is always positive.” “x~2 is always greater than zero.” “The function definition domain must have a positive number within the radical.” “The equation ax~2+bx+ If c=0 has a real root, then the discriminant △ ≥ 0. ”“ To make the unary quadratic inequality ax 2+ bx + c> 0 holds true for any real number x, the discriminant △ <0. ”a zero times The power is 1“ ”R=R~+∪R~-" where R represents a real number set, and R~+ and R~- represent a positive set and a negative set, respectively.