Respuesta :
Answer:
So, 5, 20, 45, 80,...5N2
Step-by-step explanation:
Divide the sequence by 5 and the answer becomes very obvious:
EX: 1, 4, 9, 16,...N2
quadratic sequence formula : an^2+bn+c
2nd difference 2a = 10
a = 5
1st difference 3a+b = 15
substitute 5 into a
3(5)+b = 15
b = 0
nth term rule : a + b + c = 5
substitute a and b values into equation
5 + 0 + c = 5
c = 0
nth term : 5n^2
2nd difference 2a = 10
a = 5
1st difference 3a+b = 15
substitute 5 into a
3(5)+b = 15
b = 0
nth term rule : a + b + c = 5
substitute a and b values into equation
5 + 0 + c = 5
c = 0
nth term : 5n^2
