7th term of a arithmetic sequence is 17 and its 17 th term is 7.
a)what is the sum of first 47 terms
Answers
Answered by
0
artist of the above text I don't
Answered by
0
Step-by-step explanation:
given ; a7 = 17, a17 = 7
to find the sum of first 47 terms
a + 6d = 17 ________1
a + 16d = 7________2
on subtracting we get => -10 d = 10 => d = -1
on substituting value of d in equation 1 or 2 we get
a - 6 = 17 => a = 23
now S47 = n/2 [ 2a + (n-1)d ]
S47 = 47/2 [ 2*23 + 46×(-1) ]
=> 47/2 [ 46 - 46 ]
=> 47/2 × 0
=> 0
therefore sum.of first 47 terms is Zero
Similar questions