Answers

2015-06-15T20:10:21+08:00
An= a1 +(n-1)d
an= 4+(25-1)d
an= 4+(24)d
an=4+(24)5
an=4+120
an=124
2 4 2
2015-06-16T00:05:11+08:00
Sn=n/2[2a+(n-1)d]
Sn=25/2[2(4)+(25-1)5]
Sn=25/2[8+(24)5]
Sn=25/2(8+120)
Sn=25/2(128)
Sn=25/2(128/2)
Sn=25(64)
Sn=1600 :)
4 3 4