Multiple choice

Which term of the series: 123, 119, 115, 111, …………… is the first negative term, if the first term is 123 and the series is infinite?

  1. 31st

  2. 33rd

  3. 32nd

  4. 29th
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The series is an arithmetic progression with a = 123 and d = -4. The n-th term is 123 + (n - 1)(-4) = 127 - 4n. We want 127 - 4n < 0, so 4n > 127, n > 31.75. The first integer n is 32.

AI explanation

This is an arithmetic progression with a first term of 123 and a common difference of -4. The formula for the nth term is a + (n - 1)d, so we set up the inequality 123 + (n - 1)(-4) < 0 to find the first negative value. Solving this gives 127 < 4n, which means n > 31.75, making the 32nd term the first negative term.

Keep practicing — related questions