Math, asked by vishalgadigoppula444, 4 months ago

If the 4th and the 9th terms of an AP are 5 and -5 respectively, which term of the AP is -15?

Answers

Answered by eswarivelan
4

Step-by-step explanation:

a4= a+3d = 5 ------------------>(1)

a9=a+8d = -5 ------------------>(2)

from eq (1)nd (2)

a+3d-a-8d = 5-(-5)

-5d = 10

d =-10/5

d = -2

therefore d = -2

substituting the value of d in eq (1)

a+3d=5

a+3(-2)=5

a-6=5

a=5+6

a=11

an=a+(n-1)d [here n will come below a]

-15=11+(n-1)-2

-15=11-2n+2

-15-13=-2n

-28=-2n

-28/-2=n

14=n

Therefore in 14th term the AP will be -15

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