Mathematics

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

Find the nth term Un of the A.P., 11, 4, -3,……. .
  • A.
    Un=19+7n
  • B.
    Un=19-7n
  • C.
    Un=18+7n
  • D.
    Un= 18-7n
  • E.
    Un= 17-7n
Correct Answer: Option D
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