the first and the last terms of an AP are 17 and 350 respectively. If the common difference is 9, how many terms are there and what is their sum?
Answers
Answered by
3
An=a+(n-1)d( by using this we can find the solution)
Given
An= 350
a=17
d=9
n=¿
so just put the value
350=17+(n-1)9
350-17=9n-9
333=9n-9
333+9=9n
342=9n
342÷9=n
38=n
show the number of term is 38
Sn = n/2(a+an)
sn=38/2(350+17)
Sn=19(367)
Sn=6973
Given
An= 350
a=17
d=9
n=¿
so just put the value
350=17+(n-1)9
350-17=9n-9
333=9n-9
333+9=9n
342=9n
342÷9=n
38=n
show the number of term is 38
Sn = n/2(a+an)
sn=38/2(350+17)
Sn=19(367)
Sn=6973
Maximus:
Mark it brain list when someone answered it
Answered by
3
Hello !
First term ( A ) = 17
Common difference ( D ) = 9
Last term ( Tn ) = 350
A + ( N - 1 ) × d = 350
17 + ( n - 1 ) × 9 = 350
17 + 9n - 9 = 350
9n = 350 - 8
n = 342/9
n = 38
Number of terms = 38.
Sn = N/2 × [ 2A + ( n -1 ) × D ]
S38 = 38/2 × [ 2 × 17 + ( 38 - 1 ) × 9 ]
=> 19 ( 34 + 333)
=> 19 × 367
=> 6973.
First term ( A ) = 17
Common difference ( D ) = 9
Last term ( Tn ) = 350
A + ( N - 1 ) × d = 350
17 + ( n - 1 ) × 9 = 350
17 + 9n - 9 = 350
9n = 350 - 8
n = 342/9
n = 38
Number of terms = 38.
Sn = N/2 × [ 2A + ( n -1 ) × D ]
S38 = 38/2 × [ 2 × 17 + ( 38 - 1 ) × 9 ]
=> 19 ( 34 + 333)
=> 19 × 367
=> 6973.
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