1) cn=c1+d*(n-1);
c4=c1+d*(4-1);
c4=c1+3d;
d=(c4-c1)/3;
d=(1,8-2,7)/3;
d= -0,3
2)an=a1+d(n-1);
a4=a1+d(4-1); a4=a1+3d; d=(a4-a1)/3;
a12=a1+d(12-1); a12=a1+11d; d=(a12-a1)/11;
(a4-a1)/3=(a12-a1)/11; (4-a1)/3=(36-a1)/11; a1=-8
1) cn=c1+d*(n-1);
c4=c1+d*(4-1);
c4=c1+3d;
d=(c4-c1)/3;
d=(1,8-2,7)/3;
d= -0,3
2)an=a1+d(n-1);
a4=a1+d(4-1); a4=a1+3d; d=(a4-a1)/3;
a12=a1+d(12-1); a12=a1+11d; d=(a12-a1)/11;
(a4-a1)/3=(a12-a1)/11; (4-a1)/3=(36-a1)/11; a1=-8