Merge branch 'vector5' of https://github.com/Chau-Nguyen-Developer/numerical-method-interpolating-polynomial into vector5

Found the bug while doing code review directly on Github vector5 branch.
Incorporate the "suggestion commit" into the code. Fixed the bug.
Merged vector5 branch into main.
Now, I need to merge changes from GitHub main into my vector5 local branch.
Want to try resolving merge conflict in programming4.cpp.

"If there is no struggle, there is no progress." - Federick Douglass

Author: NgocChauNguyen-CPP

programming4.cpp

@@ -87,7 +87,7 @@ int main()
     // for(size_t i = 1; vector4.size(); ++i)
     // {
     //     vector5.push_back((vector4[i] - vector4[i -1]) / (vector1[i + 2] - vector1[i -1]));
-    //     std::cout << vector5[i] << std::endl;
+    //    std::cout << vector5[i-1] << std::endl;
     // }
 
     std::cout << "Print out first part";