上面,我们介绍了形式为 x2=a的一元二次方程,它的根有三种情况: 当a>0时,方程有一对互为相反数的根,即这里的 可能是有理数,也可能是无理数. 当a=0时,方程只有一个根,即0,这种情形也可说成是有两个相同的根. 当a<0时,方程没有实数根. 有的一元二次方程的形式初看不是x2=a的样子,但是稍微做一点不影响同解的变形,就可以转化为x2=a的形式.如前面的练习中就 In the above, we introduced the unary quadratic equation of the form x2=a. There are three cases of its root: When a>0, the equation has a pair of opposite roots, that is, it may be a rational number or it may be an irrational number. When a=0, the equation has only one root, that is, 0. This case can also be said to have two identical roots. When a<0, the equation does not have a real number root. There is a form of a one-dimensional quadratic equation. Do not look like x2=a, but do something a bit that doesn’t affect the deformation of the same solution. It can be converted to x2=a. As in the previous exercise