6th step is wrong
=4n[-1/2(1+n)]
=4n-(1-n/2)
=8n-1-n/2
=7n-1/2
-3
Priyanka answered this
Answer:
-11
Priyanka answered this
Answer:
1
Sharanya answered this
Hey guys....it's a really nice question isn't it? And yes,the answer is 7n-1/2. Here's how I attempted it.
47
Sharanya answered this
If that picture isn't clear....
28
Athira Suresh answered this
3n2 - n is wrong.
7n-1/2 is the right answer.
1
Merit Nation answered this
Please view this image:
hope I helped!
1
Ashish Narang answered this
thanks
3
Aditya Gupta answered this
a=4-1/n
d=-1/n
Sn=n/2(4-1/n + (n-1)-1/n)
=n/2{2(4n -1) -n +1} n =n/2 {8n-2 -n +1}
n
=n/2{7n - 1}
n
=n/2 * 7n -1
n =1/2[7n-1]
0
Naznin Naufal answered this
7n-1/2
-3
Samya answered this
This is the ans... I hope it will help u...
Thank u :)
22
Priyankar Malla answered this
(7n-1)÷2
0
Devansh Rawat answered this
Here is the answer
1
Sangam answered this
here is the answer to the above question
2
Madbjh answered this
likhna nahi no. 4. likna nahi aata nahi aur uper se hume confuse kararha hai
-4
Rahul answered this
Hlo this is the correct answer
1
Utkarsh Vardhan Singh Rathore answered this
7n-1/2 is the correct answer.......
7
Anshika Singh answered this
a=4-1/n
d=a2-a1
=-1/n
therefore , on putting these values in the formula.....
Sn=n/2[2a+{n-1}d]
on solving further.....
we get,....
Sn=7n-1/2 HOPE THIS HINT HELPS !!