曲线与直线相切,大家惯用一元二次方程判别式Δ=0来解题,这是通法通则;但如果把它当作万能的公式,凡遇此类试题,不假思索,都采用判别式来解决,不能不说这是一种遗憾.其实用Δ=0解决切线问题运算有时极为繁杂,绝不是最佳的方法.现列举几例供大家参考. The curve is tangent to a straight line. Everyone uses the discriminant of the quadratic equation Δ = 0 to solve the problem. This is the general rule of law. However, if it is considered as a universal formula, all such tests are accepted without any thinking To solve, can not but say that this is a pity. In fact, the use of Δ = 0 to solve the problem of tangent operation is sometimes extremely complicated, by no means the best way .Considering a few for your reference.