Analysis and Approaches for IBDP Maths Ebook 1 | Page 62

Your Practice Set – Analysis and Approaches for IBDP Mathematics
19
Paper 2 Section A – Finding
and with given and
Example
Solution
In an arithmetic sequence, S30 � 5430 and u30 � 355 . Find the value of u
1
and of d .
30
S30 � �u1 � u30
�
2
(M1) for correct formula
30
5430 � 1
355�
2 u A1
u � A1 N2
1
7
u30 � u1 � (30 � 1) d
(M1) for correct formula
355 � 7 � (30 � 1)d
A1
d � 12
A1 N2
[6]
[6]
Exercise 19
1. In an arithmetic sequence, S80 �� 5320 and u80 �� 185 . Find the value of u
1
and of d .
[6]
2. In an arithmetic sequence, S96 � 4512 and u96 � 85 . Find the value of u
1
and of d .
[6]
3. In an arithmetic series, the third term is 90 and the sum of the first 10 terms is 1375.
(a)
(b)
Find the first term and the common difference.
Find the value of the 19th term.
[6]
[2]
4. In an arithmetic series, the ninth term is 276 and the sum of the first six terms is 5880.
(a)
(b)
Find the first term and the common difference.
Find the sum of the first 12 terms.
[6]
[2]
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