Question

find the 31st term of an ap whose 11th term is 88 and 16 term is 73 which term of this series will be the 1th negative term ?​

Answer 1

Answer:

11th term=88

An=88, n=11

An=a+(n-1)d

A11=a+(11-1)d

88=a+10d--eq1

16th term=73

An=73, n=16

An=a+(n-1)d

A16=a+(16-1)d

73=a+15d--eq2

Add eq1and eq2, we get

5d=(-15)

d=(-15)/5

d=(-3)

Substitute d=(-3) in eq1

a+10d=88

a+10(-3)=88

a-30=88

a=88+30

a=118

31st term

a=118, d=(-3)

An=a+(n-1)d

A31=118+(31-1)(-3)

A31=118+(30)(-3)

A31=118-90

A31=28

Therefore, the 31st term of an ap is 28.

Answer 2

31st term = 28

41st term is first negative term of the following AP

Full answer is in the above attachment!

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