怎么利用C语言解方程

#include "math.h"typedef struct { double* coef; int n;}poly;double dfx(poly* p, double v) { double t = v; double r = 0; double* coef = p->coef; int i; r += coef[1]; for (i = 2; i n ; i++) { r += coef[i]*i*t; t *= v; } return r;}do