Find the sum of first 28 terms?

[nirajnishad]

Homework Statement

sum of first 11 terms of Ap is 17 and sum of first 17 terms is 11
find the sum of first 28 terms?

Homework Equations

Sum=n/2[2a+(n-1)d]

The Attempt at a Solution

i tried solving it by using obove formula but i am not able to do so as the value of d is coming in fraction

 

[rock.freak667]

Just sub in the information and get the values for 'a' and 'd' via solving the equations simultaneously.

 

[nirajnishad]

i tried but after soving the equations, value of d is coming in fraction.and the common difference cannot be a fraction number

 

[rock.freak667]

i tried but after soving the equations, value of d is coming in fraction.and the common difference cannot be a fraction number

and why not?

 

[dharavsolanki]

Yes, why cannot the common difference be a fraction? Are 1, 1.25, 1.5, 1.75, 2 not n AP?

Hey Niraj, keep posting your dobts on PF here, we need a lot of warming up to do!

 

[statdad]

i tried but after soving the equations, value of d is coming in fraction.and the common difference cannot be a fraction number

The common difference can be a whole number, fraction, irrational number, as well as positive or negative. Finding a fraction most certainly is not an indication of an error on your part.