hey
please answer !!!
Attachments:
Answers
Answered by
0
General formula for an AP : an = a1 + (n - 1)d
When n = 4 ( 4th term)
0 = a1 + (4 - 1)d
a1 + 3d = 0
a1 = - 3d --------------------------- [ 1 ]
When n = 42 (42nd term)
-95 = a1 + (42 - 1)d
-95 = a1 + 41d
a1 = -41d - 95 --------------------------- [ 2 ]
Solve for the difference:
equate [ 1 ] and [ 2 ]:
- 3d = - 41d - 95
38d = -95
d = -5/2 ------------------ [ sub into 1 ]
Solve for the first term:
a1 = - 3 (-5/2)
a1 = 15/2
Find the AP:
an = a1 + (n - 1)d
an = 15/2 + (n - 1) (- 5/2)
an = 15/2 - 5/2 n + 5/2
an = 10 - 5/2 n
Find the number of terms:
an = 10 - 5/2 n
-125 = 10 - 5/2 n
5/2 n = 135
n = 54
Answer: The first term is 15/2 and there are 54 terms in this AP.
Anonymous:
Answer :- first term 15/2 and no of terms 54 . , Apka answer galat aaya h
Wiat .. let me checka gain ...
Okay. Found the mistake and corrected. I have also put them in fraction instead of decimals since your answer is in fraction.
Thankeww
Similar questions