7th and 19th terms of an A.P. are respectively 148 and 100. Which term

1.	7th and 19th terms of an A.P. are respectively 148 and 100. Which term of A.P. will be zero
Answer» Answer: Let a and d be the first TERM and the COMMON DIFFERENCE of the given AP RESPECTIVELY. Then, a19=52⇒a+18d=52 ...(1) a38=148⇒a+37d=148 ...(2) On subtracting (1) from (2), we get 19d=96⇒d=1996 Putting d=1996 in (1), we get a=52−18×1996=19−740 Now, S56=256[2a+(56−1)d] ∴S56=28[193800]=5600 This is your Answer

7th and 19th terms of an A.P. are respectively 148 and 100. Which term of A.P. will be zero

Answer»

Answer:

Let a and d be the first TERM and the COMMON DIFFERENCE of the given AP RESPECTIVELY. Then,

a19=52⇒a+18d=52 ...(1)

a38=148⇒a+37d=148 ...(2)

On subtracting (1) from (2), we get

19d=96⇒d=1996

Putting d=1996 in (1), we get

a=52−18×1996=19−740

Now, S56=256[2a+(56−1)d]

∴S56=28[193800]=5600

This is your Answer