plz solve this question ,question. no. 8
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3
S= 2n + 3n^2
put n= 1, u will get first term
S1 = 2 + 3 = 5
For Second term
S( n= 2) - S( n= 1)
2(2) +3( 2^2) - 5
4 + 12 -5
11
So AP is 5,11, 17....
rth term = 5 + ( r-1) 6
put n= 1, u will get first term
S1 = 2 + 3 = 5
For Second term
S( n= 2) - S( n= 1)
2(2) +3( 2^2) - 5
4 + 12 -5
11
So AP is 5,11, 17....
rth term = 5 + ( r-1) 6
akansha71:
a2 find krne ke liye subtract kyon kiya
Haan mujhe pata hai
ohk
but confusion tha
thanks
Answered by
1
Answer:
Step-by-step explanation:
given-- sn=(2n+3n^2)
when n=1, s1= 2*1+3*1^2=2+3=5 therefore a=5
n=2, s2= 2*2+3*2^2 = 4+ 12 =16 therefore a2=16-5=11
hence d= 11-5 =6
therefore AP is 5,11,17,23......
and rth term is
ar = a+(r-1)d
=5+(r-1)6
=5+6r-6
ar= 6r-1
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