一元二次方程一般形式:ax^2+bx+c=0 (a不等于0)
首先要满足判别式b^2-4ac>=0,才可能有根.
接着是利用根与系数的关系:
x1+x2=-b/a
x1*x2=c/a
当b^2-4ac>=0,且-b/a>0 且c/a>0 时,方程两根都为正,
当b^2-4ac>=0,且-b/a0 时,方程两根都为负,
只要当c/a
一元二次方程的根何时都为正?何时都为负?何时一正一负?
一元二次方程的根何时都为正?何时都为负?何时一正一负?
数学人气:113 ℃时间:2020-01-30 08:45:12
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