Question

in an a.p a3=13 a20=158 find a25
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Answer 1

Answer:

$\frac{2411}{17}$

Step-by-step explanation:

$a_{3}=a +2d =13$ -----------------------(1)

$a_{20}=a+19d=158$ --------------------(2)

Here, a = first term

            d = common difference.

(2)-(1)  => 17d = 145.

  => d = 145/17.

And   a = 13-2d = -69/17.

Therefore, $a_{25}=a+24d = -\frac{69}{17} +24(\frac{145}{17} )$

                  $a_{25}=\frac{2411}{17}$

Answer 2

a3=13

a20=158

a3+17d=a20

13+17d=158

17d=145

d=145/17

d=8.5

a20+5d=a25

158+5(8.5)=a25

158+42.5=a25

a25=200.5

ANSWER IS 200.5

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