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
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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
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Answer:
54
Step-by-step 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
Answer:
54
Step-by-step explanation: