View Compilation Error

0_0_18062658_12253.cpp: In function 'int main()':
0_0_18062658_12253.cpp:15:9: error: 's1' was not declared in this scope
         s1=a/3*x3*x3*x3+(b-k)/2*x3*x3+(c-t)*x3;
         ^
0_0_18062658_12253.cpp:16:9: error: 's2' was not declared in this scope
         s2=a/3*x2*x2*x2+(b-k)/2*x2*x2+(c-t)*x2;
         ^