The 5th term of an Arithmetic sequence is 20 and the 8th term is 32 What is the first term of this sequence ?
Answers
Answered by
1
Answer:
FIRST TERM IS 4.
Step-by-step explanation:
Answered by
0
Answer:
4
Step-by-step explanation:
TO KNOW :- aₙ= a + (n - 1) d
Here ,
a{n} → 'n'th term.
a → 1st term.
n → Number of terms.
d → Common difference.
SOLUTION :-
♦ 5th term of A.P is 20.
We have ,
n = 5
a{5} = 20
Putting values ,
20 = a + (5 - 1)d
20 = a + 4d --------(1)
Also,
♦ 8th term is 32.
We have,
a{n} = 32
n = 8
Putting values ,
→ 32 = a + (8-1)d
→ 32 = a + 7d ---------(2)
Subtracting equation (2) by equation (1) ,
→ 20 - 32 = a + 4d - (a + 7d)
→ -12 = a + 4d - a - 7d
→ -12 = -3d
→ d = -12/-3
→ d = 4
Hence , Common difference is 4.
Putting d = 4 in equation (1) ,
→ 20 = a + 4d
→ 20 = a + 4(4)
→ 20 = a + 16
→ a = 20 - 16
→ a = 4
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