Advertisements
Advertisements
प्रश्न
Find the 12th from the end of the A.P. – 2, – 4, – 6, …; – 100.
उत्तर
A.P. = – 2, – 4, – 6, …; – 100
a = –2, d = –4 – (–2)
= –4 + 2
= –2
l = –100
∴ Tn = a + (n – 1)d
⇒ –100 = –2 + (n – 1) x (–2)
⇒ –100 = –2 – 2n + 2
⇒ +2n = 100
⇒ n = `(100)/(2)` = 50
Let mth term is the 12th term from the end
Then m = l – (n – 1)d
= – 100 – (12 – 1) x (– 2)
= – 100 + 22
= – 78.
APPEARS IN
संबंधित प्रश्न
Find three numbers in A.P. whose sum is 24 and whose product is 440.
For an A.P., show that (m + n)th term + (m – n)th term = 2 × mthterm
The sum of the 4th and the 8th terms of an A.P. is 24 and the sum of the sixth term and the tenth is 44. Find the first three terms of the A.P.
If the first term of an A.P. is – 18 and its 10th term is zero, then find its common difference.
Which term of the A.P. `18, 15(1)/(2)`, 13, ... is – 47?
Which term of the A.P. 53, 48, 43,… is the first negative term?
The 15th term of an A.P. is 3 more than twice its 7th term. If the 10th term of the A.P. is 41, find its nth term.
The sum of 5th and 7th terms of an A.P. is 52 and the 10th term is 46. Find the A.P.
The sum of three numbers in A.P. is 30 and the ratio of first number to the third number is 3 : 7. Find the numbers.
Justify whether it is true to say that the following are the nth terms of an A.P. n2 + 1
