How many terms are in AP if a = 7, d= 4 and an
39
Answers
Answered by
1
Step-by-step explanation:
an is 39
a=7
d=4
We know,
an=a+(n-1)d
39=7+(n-1)4
39=7+4n-4
39=3+4n
4n=36
n= 9
Therefore number of terms is 9
Answered by
1
EXPLANATION
- GIVEN
First term = a = 7
common difference = d = b - a = 4
An = 39
TO FIND HOW MANY TERMS ARE IN AP.
FORMULA OF NTH TERMS OF AN AP.
An = a + ( n - 1 ) d
now we can substitute the value of
first term, common difference, n terms
we get,
39 = 7 + ( n - 1 ) 4
39 = 7 + 4n - 4
39 = 4n + 3
36 = 4n
n = 9
Therefore,
Terms are in Ap = 9 terms
MORE INFORMATION.
Tn = a + ( n - 1 ) d
where,
a = first term
d = common difference
n = number of terms
Sn = n/2 ( 2a + ( n - 1 ) d)
where,
a = first term
d = common difference
n = number of terms
Sn = sum of n terms of an Ap
CONDITIONS OF AN AP.
2B = A + C
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