Answers

2016-04-03T14:44:14+05:30
A=3,n=25,d=7-3=4
S₂₅=n/2(2a+(n-1)d)
S₂₅=25/2[2(3)+(25-1)4]
S₂₅=25/2(6+96)
S₂₅=25/2(102)
S₂₅=25(51)
S₂₅=1275.

0
If nth term would be 100, that doesn't mean that there are 100 terms......... For ex-----. AP-- 5,10,15,20.........100,,, so here there will be 20 terms. Not 100...... Similarly in the ques. nth term is 25.... So with the formula of nth term we'll take out the value of n ( no. Of terms)
Okay in the ques. Its 25 terms.... I thought 25 is an
Sorry
haha ok finally u realized
Yeah
2016-04-03T20:14:29+05:30
Sn= n/2[ 2a+(n-1) d].......... Here a=3,,,,,, d= 7-3= 4..... and n= 25.... S25= 25/2[6+24×4]..................... S25= 25/2[6+ 96]............................. S25= 25/2[102]........ Now, 102 is cancelled fro. 2... 51 remains...... S25= 51×25............. S25= 1275
1 5 1
Hey plzz mark it as best...
but answer is 1275
Yeah... I have edited it.... I wrote by mistake 100 instead of 102