在计算过河缆的缆道拉力时,总要遇到一个型同H~3+BH~2-C=0的三次方程。如果直接对此方程试算求根,由于B、H、C各值是四位以上的数字,所以在运算时比较麻烦;而更主要的是很难得到较为满意的解答。试算中在假定很多H的情况下,还常常出现H~3+BH~2-C≠0,且其数字和0相差甚远,例如2×10~(10) When calculating the cable channel tension of a riverway, a cubic equation with the same type of H~3+BH~2-C=0 is always encountered. If we try to root this equation directly, because the values ​​of B, H, and C are four or more digits, it is more troublesome to compute; and more importantly, it is difficult to obtain satisfactory answers. In the trial calculation, when H is assumed to be many, H~3+BH~2-C≠0 often appears, and its number is far from 0, for example, 2*10~(10).