Question

If sum of the 3rd and 8th term of an ap is 7 and the sum of the 7th and 14th term is -3.find the 10th term

Answer 1

This is the answer and this is very simple to do it. You get one or two models in board exam do practise it well. And this chapter is easy to score. All the best my friend!!

Answer 2

Answer:

3rd term(a3)=a+2d

8th term(a8)=a+7d

14th term(a14)=a+13d

10th term(a10)=a+9d

Given the sum of the 3rd and 8th term is 7.ie,

( a+2d)+(a+7d)=7

2a+9d=7--------(1)

Also the sum of the 7th and 14th term is -3.ie,

(a+6d)+(a+13d)=(-3)

2a+19d=(-3)-------(2)

By subtracting eq(2) from (1)

2a+9d=7. 2a+9d=7

- {2a+19d=(-3)} -2a-19d=+3

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0(-10)d=10

d=10\(-10)

d=(-1)

Substituting the value of d to any one equation

2a+9d=7

2a+9x(-1)=7

2a-9=7

2a=7+9

2a=16

a=16/2

a=8

Therefore a10=a+9d

=8+9x(-1)

=8+(-9)

=8-9

=-1

Therefore 10th term a10 = -1

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