Answer:
an = 40 - 3n
Read down to get the alternate answer.
Step-by-step explanation:
an = a1 + (n - 1)*d
a2 = a1 + (2 - 1)d
34 = a1 + d
a7 = a1 + 6*d
19 = a1 + 6d
34= a1 + d Subtract
-15 = 5d Divide by 5
d = - 3
Now use the first equation to find a2
a1 + d = 34
a1 -3 = 34 Add 3
a1 = 34 + 3
a1 = 37
The formula you want is
an = 37 + (n - 1)*-3 You could reduce it further. Remove the brackets
an = 37 - 3n + 3
an = 40 - 3n
Does it work? Try a7
19 = 40 - 3*7
19 = 40 - 21
19 = 19
Yes it works.
