find the 20th term from the last term of the AP:3,8,13,....253
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Answered by
5
a = 3
d = T2 - T1 = 8 - 3 = 5
L = 253
=> a + (n-1)d = 253
=> 3 + (n-1)( 5) = 253
=> (n-1)(5) = 250
=> n - 1 = 50
=> n = 51
Total number of terms = 51
20th term from the last is the 32nd term from beginning.
Required term = T32
= a + 31d
= 3 + 31 × 5
= 3 + 155
= 158
d = T2 - T1 = 8 - 3 = 5
L = 253
=> a + (n-1)d = 253
=> 3 + (n-1)( 5) = 253
=> (n-1)(5) = 250
=> n - 1 = 50
=> n = 51
Total number of terms = 51
20th term from the last is the 32nd term from beginning.
Required term = T32
= a + 31d
= 3 + 31 × 5
= 3 + 155
= 158
shiv7598:
right answer
thanks
ur most welcome bro :)
Thanks
Answered by
7
Solution :
We have, l = Last term = 253
and,
d = Common difference = 8 - 3 = 5
∴ 20th term from the end = l - (20 - 1)d
= l - 19d
= 253 - 19 × 5
= 253 - 95 = 158
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