Question

The 51st, 11th and the last terms of an AP are 0,8,-1/5 respectively. Find common difference and no. of terms. ​

Answer 1

Step-by-step explanation:

given

a51 = 0

a11 = 8

an = -1/5

now ,

a51 = a + 50d = 0 --------eq (1)

a11 = a + 10d = 8 --------eq (2)

subtracting eq (2) from (1)

we get ,

40d = -8

d = -8/40 =-1/5 = common difference

put value of d in eq 2

a + 10x-1/5 = 8

=a-2 = 8

a=10

now ,

an = a+ (n-1)d

-1/5 = 10 + (n-1)-1/5

-1/5-10= (n-1)-1/5

-51/5 x-5= (n-1)

(n-1) = 51

n =52 = number of term