Find sum of following A.P.:
(a) 8 + 13 + 18 + ……………+ 128
Answers
Answered by
0
Answer:
8+13+18+23+28+33+38+43+48+53+58+63+68+73+78+83+88+93+98+103+108+113+118+123+128
Step-by-step explanation:
this is because it has a pattern of adding number by 5
Answered by
0
Answer:
1700
Step-by-step explanation:
Sₙ=n/2[2a+(n-1)d]
given tₙ=128
a+(n-1)d=128
8+(n-1)5=128
5n+3=128
n=25
hence S₂₅=25/2[2(8)+(24)5]
=25/2[16+120]
= 25[68]
=1700
hope this helps you
mark me as the brainliest
Similar questions