How many terms
terms of the AP -6,-11/2,-5___ are needed to give the sum – 25
Answers
Answered by
6
The value of "number of terms (n) is 5".
Step-by-step explanation:
The given sequence are - 6, - , - 5, ......
Here, first term(a) = - 6 and
common difference (d) = - + 6 =
Given, = - 25
We know that,
= ·{2a + ( n- 1)d}
⇒ ·{2( - 6) + ( n- 1) × } = - 25
⇒ ·{ - 12 + - } = - 25
⇒ - 25n + 100 = 0
⇒ - 20n - 5n + 100 = 0
⇒ (n - 20)(n - 5) = 0
∴ n = 5 or 20 [∵ n = 20 is not satisfied]
n = 5
Hence, the value of "number of terms (n) is 5".
Similar questions
Computer Science,
5 months ago
English,
5 months ago
Physics,
5 months ago
Business Studies,
9 months ago
Business Studies,
9 months ago
Physics,
1 year ago