iGCSE Mathematics (0580) :E2.7 Continue a given number sequence.iGCSE Style Questions Paper 4

Question

 (a) Naga has n marbles.
Panav has three times as many marbles as Naga.
Naga loses 5 marbles and Panav buys 10 marbles.
Together they now have more than 105 marbles.
Write down and solve an inequality in n.
………………………………………….
(b) y is inversely proportional to \(x^{2}.\)
When x = 4, y = 7.5.
Find y when x = 5.
y = ………………………………………….
(c) Find the nth term of each sequence.
(i) 4    2   0  -2    -4 …
………………………………………….
(ii) 1  7   17   31    49 …
………………………………………….

Answer/Explanation

(a) n − 5 + 3n + 10 > 105 or better
n > 25 final answer
(b) 4.8
(c)(i) 6 − 2n final answer
(ii) \(2n^{2}-1\) final answer

Question

(a) The table shows the first five terms of sequence A and sequence B.

(i) Complete the table for the 6th term of each sequence. [2]

(ii) Find the nth term of

(a) sequence A,[2]

(b) sequence B.[2]

(b) The nth term of another sequence is 4n2+n+3.

Find

(i) the 2nd term, [1]

(ii) the value of n when the nth term is 498.

n = [3]

Answer/Explanation

Ans:

11(a)(i) 77 243

11(a)(ii)(a) 2n2+5 oe

11(a)(ii)(b) 3n-1oe

11(b)(i) 21

11(b)(ii) 11

Question

(a) Complete the table for the 5th term and the nth term of each sequence. [11]

(b)     0,      1,     1,     2,     3,     5,     8,     13,     21, …

       This sequence is a Fibonacci sequence.
       After the first two terms, the rule to find the next term is “add the two previous terms”.
       For example, 5+8= 13.

       Use this rule to complete each of the following Fibonacci sequences.[3]

2   4   _   _   _ 
1   _   _   _  11
_   -1  _   _  1

(c)      \(\frac{1}{3}\),     \(\frac{3}{4}\),     \(\frac{4}{7}\),     \(\frac{7}{11}\),     \(\frac{11}{18}\),     …

(i) One term of this sequence is \(\frac{p}{q}\).

      Find, in terms of p and q, the next term in this sequence.[1]

(ii) Find the 6th term of this sequence.[1]

Answer/Explanation

Ans:

10(a) – 7
           13 – 4n oe

           36
           (n + 1)2oe

           125
           n3 oe

           128
           2n + 2 oe

10(b) _,    _,   6,   10,  16
           _,    3,    4,    7,    _
           2,    _,    1,    0,    _

10(c)(i)  \(\frac{q}{p+q}\)

10(c)(ii) \(\frac{18}{29}\)

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