Answer:
-10
Explanation:
t3 = a1 + (n - 1)*d
t3 = a1 + (3 -1)*d
2 = a1 + 2d
t17 = a1 + (n - 1)*d
-40 = a1 + 16d Put the first condition underneath and subtract
2 = a1 + 2d
-42 = 14 d
d = - 3
2 = a1 + 2*(-3)
2 = a1 - 6 Add 6 to both sides
2 + 6 = a1
a1 = 8
Now you want the 7th term
t7 = a1 + (n - 1)*d
t7 = 8 + (7 - 1)*d
t7 = 8 + 6*(-3)
t7 = 8 - 18
t7 = - 10