b8=b1+7d , d=(b8-b1)/7 , d =(40-5)/7=5
Sn=2a1+d(n-1)/2×n
S10=2×5+5×9/2×10
S10= 55/2×10
S10= 275
Copyright © 2024 SCHOLAR.TIPS - All rights reserved.
Answers & Comments
b8=b1+7d , d=(b8-b1)/7 , d =(40-5)/7=5
Sn=2a1+d(n-1)/2×n
S10=2×5+5×9/2×10
S10= 55/2×10
S10= 275