Find the nth term Un of the A.P., 11, 4, -3,……. .

Explanation

A.P 11, 4, -3
1st term = 11
A.P = a, a + d, a + 2d ...... a + (n - 1)d
If a = 11
a + d = 4
d = 4 - 11 = -7
nth term = a + (n-1)d
         = 11 + (n-1)(-7)
         = 11 - 7n + 7
         = 18 - 7n