The first and the last term of an A.P are 17 and 350 respectively. If the common difference is 9 how many terms are there in A.P and what is their sum?
Answers
Answered by
992
Hi ,
let a and d are first term and common
difference for an AP.
number of terms of AP = n
last term = nth term = l = an
a = 17 , d = 9 ,
l = 350
a + ( n - 1 ) d = 350
17 + ( n - 1 ) 9 = 350
( n - 1 ) 9 = 350 - 17
( n - 1 ) 9 = 333
n - 1 = 333 / 9
n - 1 = 37
n = 37 + 1
n = 38
Therefore ,
number of terms in given AP = n = 38
sum of n terms of AP = Sn
Sn = n /2 ( a + l )
here n= 38
S38 = 38 / 2 [ 17 + 350 ]
= 19 × 367
= 6973
I hope this helps you.
:)
let a and d are first term and common
difference for an AP.
number of terms of AP = n
last term = nth term = l = an
a = 17 , d = 9 ,
l = 350
a + ( n - 1 ) d = 350
17 + ( n - 1 ) 9 = 350
( n - 1 ) 9 = 350 - 17
( n - 1 ) 9 = 333
n - 1 = 333 / 9
n - 1 = 37
n = 37 + 1
n = 38
Therefore ,
number of terms in given AP = n = 38
sum of n terms of AP = Sn
Sn = n /2 ( a + l )
here n= 38
S38 = 38 / 2 [ 17 + 350 ]
= 19 × 367
= 6973
I hope this helps you.
:)
Answered by
105
Answer:6973.
Step-by-step explanation:
let a and d are first term and common
difference for an AP.
number of terms of AP = n
last term = nth term = l = an
a = 17 , d = 9 ,
l = 350
a + ( n - 1 ) d = 350
17 + ( n - 1 ) 9 = 350
( n - 1 ) 9 = 350 - 17
( n - 1 ) 9 = 333
n - 1 = 333 / 9
n - 1 = 37
n = 37 + 1
n = 38
Therefore ,
number of terms in given AP = n = 38
sum of n terms of AP = Sn
Sn = n /2 ( a + l )
here n= 38
S38 = 38 / 2 [ 17 + 350 ]
= 19 × 367
= 6973
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