Question

find ap if a5=9 ,a13-a9=20
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Answer 1

Answer:

this is your answer

Step-by-step explanation:

a=7,a

13

=35

a

13

=a+(13−1)d

35=7+12d

28=12d

d=28/12=7/3

s

13

=

2

13

[2a+(13−1)

3

7

]

s

13

=

2

13

[14+(12)

3

7

]

s

13

=

2

13

[14+28]

s

13

=13×21

s

13

=273