View Compilation Error

0_0_17956097_20129.cpp: In function 'int Judge(std::string)':
0_0_17956097_20129.cpp:12:27: error: 'pow' was not declared in this scope
   x+=(a[i]-'0')*pow(10.0,k);
                           ^
0_0_17956097_20129.cpp:21:19: error: 'sqrt' was not declared in this scope
   x=sqrt((double)x);
                   ^