分数系列2/1,-3/2,5/3,-8/5,13/8,-21/13,.求这个数列的前20项之和.如题用C++语言编出来谢谢!

Question

分数系列2/1,-3/2,5/3,-8/5,13/8,-21/13,.求这个数列的前20项之和.如题
用C++语言编出来谢谢!

Answer 1

#include using namespace std; int main() { int i; double a, b, c; double sum = 0, tf = 1; a = b = 1; for(i = 0; i < 20; ++i) { c = a + b; sum += c / b * tf; a = b; b = c; tf = -tf; } cout