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Arithmetic Progressions

Question
CBSEENMA10007585
Wired Faculty App

In an AP
Given a12 = 37, d = 3, find ‘a’ and S12.

Solution

Here,    a12 = 37,   d= 3
We know that,
      an = a + (n - 1)d
rightwards double arrow a12 = a + (12 - 1) x 3
rightwards double arrow 37 = a + 11 x 3
rightwards double arrow  a = 37 - 33 = 4
And,     straight S subscript straight n space equals straight n over 2 straight x space left parenthesis straight a plus straight l right parenthesis therefore space space space straight S subscript 12 equals 12 over 2 straight x space left parenthesis 4 plus 37 right parenthesis space space space space space space equals space 6 straight x space 41 space equals space 246 Hence comma space space space straight a space equals space 4 and space straight S subscript 12 space equals space 246 end subscript 

Some More Questions From Arithmetic Progressions Chapter

Write first four terms of the AP, when the first term a and the common difference d are given as follows:
a – 10, d = 10

Write first four terms of the AP, when the first term a and the common difference d are given as follows:
a = –2, d = 0

Write first four terms of the AP, when the first term a and the common difference d are given as follows:
a = 4, d = – 3

Write first four terms of the AP, when the first term a and the common difference d are given as follows:

a = – 1.25, d = – 0.25

For the following APs, write the first term and the common difference
3, 1, – 1, – 3, . . .

For the following APs, write the first term and the common difference
– 5, – 1, 3, 7, . . .

For the following APs, write the first term and the common difference
0.6, 1.7, 2.8, 3.9, . . .

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