Question

if 3rd term of an A. P. is 18 and 7th term is ​

Answer 1

ya to 4 h answer ya 3 h......

Answer 2

$\huge\underline\mathfrak\red{Answer:}$

if 3rd term of an A. P. is 18 and 7th term is 612.

Step By Step explanation:

Let the first term of an AP be a and common difference be d

The third term of an AP is a+2d, given that it is equal to 18

⇒a+2d=18

The seventh term of an AP is a+6d, given that it is equal to 30

⇒a+6d=30

By subtracting first equation from second equation , we get 4d=12

⇒d=3

By substituting the value of d it in first equation, we get a=12

Therefore, sum of first 17 terms in AP is

Therefore, sum of first 17 terms in AP is 17/2 (2×12+(17−1)×3)=

Therefore, sum of first 17 terms in AP is 17/2 (2×12+(17−1)×3)= 17/2 ×72= 612

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