Question

the sum of all terms of an A.p having 10 terms except for the first term is 81 , except for the fourth term ,60,find the second term of the AP​

Answer 1

Answer:

Step-by-step explanation

No.of terms=10,a1=81,a4=60 we know an=a+(n-1)d therefore a4=60 60=81+(4-1)d

We get d=-7

Sn=n÷2(2a+(n-1)d)

Here n=10,a=81,d=-7

By solving we get sn=505

Answer 2

Given:

the sum of all term of AP = 10

The first term, a1 = 81

The fourth term, a4 = 60

Formula:

The formula for the nth term of an arithmetic progression is :

aₙ =  a + (n - 1) d

Where d is the common difference between the terms

n is the nth term, and a is the first term

therefore, calculating for the fourth term in order to get the value of d:

a4 = a + (4 - 1) *d

60 = 81 + (3)*d

60-81 =5d

-21 = 3d

d = -21/3

d= -7

Calculating the second term using formula:

aₙ =  a + (n - 1) d

a= 81

n=2

d=-7

a2 = 81 + (2-1) *-7

a2 = 81 -7

a2 = 74

Hence, the second term of the AP is 74

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