In an A.P a=2, n=16, s16=392, d=?.
Answers
Answer:
Sn = a+(n-1)d
392= 2+(16-1)d
390 = 15d
d. = 390/15
d = 26
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Step-by-step explanation:
Given :-
In an A.P ,a = 2 ,n=16, s16=392
To find :-
Find the value of d ?
Solution :-
Given that
In an AP ,
First term (a) = 2
number of terms (n) = 16
Let the Common difference be d
Sum of first 16 terms (S16) = 392
We know that
Sum of first n terms in an AP is
Sn = (n/2)[2a+(n-1)d]
On substituting these values in the above formula then
=> S16= (16/2)[2(2)+(16-1)d]
=> (8)[4+(15d)] = 392
=> (8)(4+15d) = 392
=> 4+15d = 392/8
=> 4+15d = 49
=> 15d = 49-4
=> 15d = 45
=> d = 45/15
=> d = 3
Therefore, d = 3
Comm difference of the AP = 3
Answer :-
The value of d for the given problem is 3
Check :-
a = 2
d = 3
n = 16
S16 = (16/2)[2×2+(16-1)(3)]
=> S16 = (8)[4+(15×3)]
=> S16 = (8)(4+45)
=> S16 = (8)(49)
=> S16 = 392
Verified the given relations in the given problem.
Used formulae:-
→ Sum of first n terms in an AP is
Sn = (n/2)[2a+(n-1)d]
- a = First term
- d = Common difference
- n = Number of terms