Question

An arithmetic sequence has a 3rd term equal to 5 and 8th term equal to -20. Find the term of the sequence that has value -130

Answer 1

Step-by-step explanation:

19 is equal to (a) 150 (b) 170 (c) 180 (d) 190 [ SSC (GL) Prel. ... + 202 = 2870, the value of (22 + 42 + 62 + . ... What is the 507th term of the sequence: 1, -1, 2, -2, 1, -1, 2, -2, 1 ...

Answer 2

$\red{ANSWER}$

a3 = 5 ,

a + 2d = 5 ---> 1

a8 = -20

a + 7d = -20 ---> 2

Solving 1 & 2

a + 2d = 5

a + 7d = -20

- - +

--------------

- 5d = 25

d = 25/-5

d = -5

Substitute the value of d = -5 in equation 1

a + 2d = 5

a + 2(-5) = 5

a - 10 = 5

a = 5 + 10

a = 15

an = a +(n - 1) d

-130 = 15 + (n - 1)(-5)

-130 = 15 - 5n + 5

-130 = 20 - 5n

-130 - 20 = - 5n

-150 = - 5n

n = 150/5

n = 30

So -130 is the 30th term of an A.P..

Thank you