Find the $20^{t h}$ term of $A P : - 5, - 5 / 2, 0, 5 / 2.....$

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Solution

Find $20^{t h}$ term of A.P
$- 5, 5 / 2, 0, 5 / 2, . . . .$
$a = - 5$
$d = b - a$
$= \frac{5}{2} - (- 5)$
$= \frac{5}{2} + 5$
$d = \frac{15}{2}$
$\to t_{n} = a + (n - 1) d$
$t_{20} = - 5 + (20 - 1) (\frac{15}{2})$
$= - 5 + 19 \times \frac{15}{2}$
$= \frac{- 10 + 19 \times 15}{2}$
$= \frac{- 10 + 285}{2}$
$= \frac{2 + 5}{2}$
$\to t_{20} = 137.5$

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Similar questions

Q. Question 4
The

11^{t h}

term of the AP

- 5, \frac{- 5}{2}, 0, \frac{5}{2}, \dots \dots

is

A) -20
B) 20
C) -30
D) 30

Q. The

25^{t h}

term of

A P

- 5, \frac{- 5}{2}, 0, \frac{5}{2} . . . . . . . . . . . .

- b

,
then what is the value of

b ?

Q. Question 4
The

11^{t h}

term of the AP

- 5, \frac{- 5}{2}, 0, \frac{5}{2}, \dots \dots

is

A) -20
B) 20
C) -30
D) 30

Q. The

11^{t h}

term of the series

- 5, \frac{- 5}{2}, 0, \frac{5}{2}, \dots

(i) the sum fo the first n terms of an AP is $(\frac{5 n^{2}}{2} + \frac{3 n}{2})$ . Find hte nth term and the 20th term of this AP.
(ii) The sum of the first n terms of an AP is $(\frac{3 n^{2}}{2} + \frac{5 n}{2})$ . Find its nth term and the 25th term.

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Find the 20th term of AP:−5,−5/2,0,5/2.....

Find 20th term of A.P−5,5/2,0,5/2,....a=−5d=b−a=52−(−5)=52+5d=152→tn=a+(n−1)dt20=−5+(20−1)(152)=−5+19×152=−10+19×152=−10+2852=2+52→t20=137.5

Find the $20^{t h}$ term of $A P : - 5, - 5 / 2, 0, 5 / 2.....$