Question

Two A.P have the same common difference.One of them starts with 5, while the others starts with 8. Then, the product of the 11th terms is 2160. Find these numbers ?

Answer 1

Step-by-step explanation:

Let the same common difference of two A.P. be d

First term of 1st AP =−1

Forth term of 1st AP =(−1+3d)

First term of 2nd AP =−8

Forth term of 2nd AP =(−8+3d)

Then (a

4

)

1stAP

−(a

4

)

2ndAP

=(−1+3d)−(−8+3d)

=−1+3d+8−3d=7

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