in an ap if common difference 2 sum of n terms is 49 7th term is 13 then n
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Answered by
66
✨d=2
Sn=49
A7=13
Sn=n/2(2a+(n-1)d)
A7=a+6d
13=a+12
✨a=1✨
now put this a in Sn equation.
49=n/2{2×1+(n-1)2}
✨Value of n=7
Sn=49
A7=13
Sn=n/2(2a+(n-1)d)
A7=a+6d
13=a+12
✨a=1✨
now put this a in Sn equation.
49=n/2{2×1+(n-1)2}
✨Value of n=7
Answered by
0
Answer:
=> n=7
Step-by-step explanation:
An A.P. is given .
comman difference (d) = 2
sum of n terms = 49
And 7th term = 13
To find the value of n.
As per question ,
by using the formula Tₙ = a + (n-1)d
T₇ = a + (n-1)d
13 = a + (7-1)2
13 = a + 6×2
13 = a + 12
a = 13 - 12
a = 1.
by using the formula
Sₙ=
Here n = 7, because terms are positive not negatives.
Therefore, n = 7 .
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