Question
The nth term of a sequence is \(an^2 + bn\).
(a) Write down an expression, in terms of a and b, for the 3rd term.
(b) The 3rd term of this sequence is 21 and the 6th term is 96.
Find the value of a and the value of b.
You must show all your working.
a = ……………………
b = ……………………
Answer/Explanation
Ans:
(a) 9a + 3b
(b) 36a + 6b = 96 or 9a + 3b = 21
for correct method to eliminate one variable
a = 3
b = -2
Question
Find the nth term in each of the following sequences.
(a) \(\frac{1}{3}\). \(\frac{2}{4}\), \(\frac{3}{5}\), \(\frac{4}{6}\), \(\frac{5}{7}\),
(b) 0, 3, 8, 15, 24, ……
Answer/Explanation
Ans:
(a) \(\frac{n}{n + 2}\) oe final answer
(b) \(n^2-1\) oe final answer
Question
7, 5, 3, 1, – 1, …
(a) Find the next term in this sequence.
(b) Find the nth term of the sequence.
Answer/Explanation
Ans:
(a) -3
(b) 9 – 2n oe