How many terms of the A.P. …
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Posted by Pratibha Gouda 6 years, 6 months ago
- 2 answers
Sneh Shrivastava 6 years, 6 months ago
a=3,d=2,n=?,An=120
So if we use the formula
An=a+(n-1)d
120=3+(n-1)2
120=3+2n-2
120=1+2n
120÷2=n+1
60=n+1
60-1=n
n=59
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Hans Raj 6 years, 6 months ago
a=3
d=2
n=?
sn=n/2(2a+(n-1)d)=120
n/2(6+2n - 2)=120
3n+n2-n=120
n2+2n-120=0
n2+12n-10n-120=0
n(n+12) - 10(n+12)=0
n = 10
n= -12 not possible
check ur answer s10 = 10/2(2a+18)
= 5(6+18)
= 5x24=120
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