Ответ:
a11=a1+10d
10d=25-10=15
d=1.5
a20=a1+d(n-1)=10+1.5(20-1)=38.5
S=(a1+a20/2)*n=(10+38.5)/2*20=485
Copyright © 2024 SCHOLAR.TIPS - All rights reserved.
Answers & Comments
Ответ:
a11=a1+10d
10d=25-10=15
d=1.5
a20=a1+d(n-1)=10+1.5(20-1)=38.5
S=(a1+a20/2)*n=(10+38.5)/2*20=485