Question

if sum of the first 14 terms of an AP is 1050 and its first term is 10,find the 20 terms

Answer 1

sum =14/2*(20+(14-1)d)=1050 then by solving this you can get cd which is 10 then you can get it

Answer 2

a (first term)=10
S (sum)=1050
no. of terms (n)=14
d is the common difference
therefore, S=n/2[2a+(n-1)d]
1050=14/2[2x10+(14-1)d]
1050/7=20+13d
150-20=13d
130/13=d
10=d

m(the term)=20
therefore, its 20 term is...
=a+(m-1)d
=10+(20-1)10
=10+190
=200