Question

the nth term of a sequence is given by an²+bn where a and b are integers the 2nd term of the sequence is 2 4th term of the sequence is 20. find the 6th term of the sequence

Answer 1

54

Explanation:

Answer 2

54

Explanation:

Tn = an²+bn

T2 = a2²+2b

2 = 4a +2b

Multiply all through by 2

4 = 8a +4b

4b = 4-8a

T4 = a4² + 4b

20 = 16a +4b

4b = 20-16a

4-8a = 20-16a

16a -8a = 20-4

8a = 16

a = 16/8 = 2

4b = 4-8a = 4-8(2) = 4-16 = -12

b = -12/4 = -3

T6 = a6² + 6b

T6 = 2(36) + 6(-3) = 72 -18 = 54