Question

which term of Ap : 3,8, 13 ,18 ••• is 78?

8th term
7th term
15 term
16 term

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Answer 1

Answer:

15 th term.................

........

Answer 2

Answer:

8th term : 38

7th term : 33

15th term : 73

16th term : 78

$a = 3 \: \: \: \: \: \\ d = 8 - 3 = 5 \\ \: \: \: a_{n} = a + (n - 1) \: d \\ \\ 8th \: \: term = 3 + (8 - 1)5 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 3 + 35 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 38 \\ 7th \: \: term \: = 3 + (7 - 1)5 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 3 + 30 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 33 \\ 15th \: term = 3 +(15 - 1)5 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 3 + 70 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 73 \\ 16th \: term = 3 + (16 - 1)5 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 3 + 75 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 78$

I hope this may help you

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