Answer:
-5
an=4-5n
a12=-56
Step-by-step explanation:
a1=-1,an=a1+d(n-1)
a2=a1+d(2-1)=-1+d=-6
so -1+d=-6
+1 +1
d=-6+1
d=-5
an=a1+d*(n-1) now I substitute a1 and d because I know them
an=-1+-5*(n-1)=-1-5n+5
an=4-5n
a12=a1+d*(12-1)
a12= -1 -5*11=-1-55
a12=-56
