Answer:
-19
Step-by-step explanation:
f(1) = 1
Substitute f(1) = 1
f(2) = f(2-1) -5
= f(1) - 5
+ (1) - 5
f(2) = -4
Substitute f(2) = -4
f(3) = f(3-1) -5
= f(2) -5
= (-4) -5
f(3) = -9
Substitute f(3) = -9
f(4) = f(4-1) - 5
= f(3) -5
= (-9) -5
f(4) = -14
Substitute f(4) = -14
f(5) = f(5-1) -5
= f(4) -5
= (-14) -5
f(5) = -19
Common difference of -5
Arithmetic Sequence:
1,-4,-9,-14,-19
