Question

The sum of the third and the seventh terms of an ap is 6 and their profuct is 8 find the sum of firstsixtee terms of the ap

Answer 1

Explaination

• If there is term ‘a3’ and ‘a7’ then there must be first place for A.P assuming it to be a1 or simply ‘a’.

• If Comman difference of terms is d [a2 - a = d] then ‘a3 = a + 2d’.

• Similarly, a7 = a + 6d.

• Find the independent values of ‘a’ and ‘d’.

• Since there are two values of d then there will be two values of ‘a’ also.

• Take a = 1;d = + ½ and a = 5;d = - ½ as two groups.

• You will obtain two possible sums of 16 terms in an A.P.

Answer 2

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