# Write the first five terms of the sequences whose n^{th} term is a_{n} = (- 1)^{n - 1} 5^{n + 1}

**Solution**:

nth term is given as a_{n} = (- 1)^{n - 1} 5^{n + 1}

Substituting n = 1, 2, 3, 4, 5

a_{1} = (- 1)^{1 - 1} 5^{1 }^{+ }^{1} = 5^{2} = 25

a_{2} = (- 1)^{2 - 1} 5^{2 }^{+ }^{1} = - 5^{3} = - 125

a_{3} = (- 1)^{3 - 1} 5^{3 }^{+ }^{1} = 5^{4} = 625

a_{4} = (- 1)^{4 - 1} 5^{4 }^{+ }^{1} = - 5^{5} = - 3125

a_{5} = (- 1)^{5 - 1} 5^{5 + 1} = 5^{6} = 15625

Therefore, the required terms are 25, - 125, 625, - 3125, and 15625

NCERT Solutions Class 11 Maths Chapter 9 Exercise 9.1 Question 5

## Write the first five terms of the sequences whose n^{th} term is a_{n} = (- 1)^{n - 1} 5^{n + 1}

**Summary:**

The questions tells us that the nth term is a_{n} = (- 1)^{n - 1} 5^{n + 1}. Therefore the terms are 25, - 125, 625, - 3125 and 15625