Question

If sum of three terms of A.P. is 21 then the middle term is
a) 3
b) 7
c) 11
53=21
S:​

Answer 1

Answer:

7 is the answer but I'm not very sure about it

Answer 2

Answer:

• The middle term is 7.

Given:

The sum of three terms of A.P. is 21.

To find:

• Middle term.

Solution:

Let the three terms in an A.P. be (a - d), a and (a + d)

According to the given condition.

(a - d) + a + (a + d) = 21

=> 3a = 21

=> a = 21/3

=> a = 7

Hence, the middle term is 7.

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Extra information:

• $\sf{t_{n}=a+(n-1)d}$

• $\sf{S_{n}=\dfrac{n}{2}[2a+(n-1)d}$