Question

Which term of the AP 123,118,113,.... is the first negative term?

Answer 1

Answer:

26th term

Step-by-step explanation:

Given AP is 123,118,113...

First term a = 123.

Common difference d = 118 - 123

                                    = -5

Let nth term be first negative term.

a(n) < 0

= a + (n - 1) * d < 0

= 123 + (n - 1) * (-5) < 0

= 123 - 5n + 5 < 0

= -5n < -128

= n > 128/5

n = 25.6

So, 26th term of the AP is the first negative term.

Hope it helps!

Answer 2

Step-by-step explanation:

a(n) < 0

a + (n - 1) * d < 0

123 + (n - 1) * (-5) < 0

123 - 5n + 5 < 0

-5n < -128

n > 128/5

n = 25.6

25th term is first negative term.