Question

Q. 84 (pls give explained answer)

Answer 1

Answer:

10th term.

Step-by-step explanation:

Please find the attached image and tell me if anything is not clear.

Answer 2

Here is your answer....

5th term of the AP is given which means

a + (5-1)d = 20

a + 4d = 20...............equation (1)

then....15th term is given which means...

a + 14d = -20............equation (2)

now subtract equation 2 from

equation 1....

4d - 14d = 20 + 20

-10d = 40

d = -4

i.e. difference of two terms if -4

put the value of d in equation 1

a + 4(-4) = 20

a - 16 = 20

a = 36

then let a + (n-1)d = 0

put values of a and d

36 + (n-1)× (-4 )= 0

(n-1)×(-4) = -36

(n-1) = 9

n = 10

hence 10th term of the given AP is zero...

hope this will help you...

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