已知方程X^3+X-4=0在区间[1,2]内有一根，用二分法求根，使其具有5位有效数字至少应二分多少次,求用C语言编

#include #include double fun(double x) { return x * x * x + x - 4; } int num=0; double root(double a, double b, double e) { double x1, x2, y1, x, y; x1 = a; x2 = b; do { x = (x1 + x2)/2; y = fun(x); y1 = fun(x1); if( ( y 0 && y1 >