Question

If $5^{th}$ and $6^{th}$ terms of an A. P are respectively 6 and 5 , find the ${11}^{th}$ term of the A. P.

Answer 1

n = a + (n-1) d

a = first term

d= Common difference

n= number of terms

I )

tn = 5 , n= 6

6= a+(5–1) d

6= a+4d ………(1)

II)

simillarly
tn=6, n = 5
5=a+5d.........................(2)

subtracting both

-d=1
d=-1
simillarly a comes out to be 10


11th terrm=a+10d
11th term=10-10=0