Question

Which term of ap is first negative 50,45,40........

Answer 1

Here , a=50

d=50-45= -5

Let the n^th term of the given AP be the first negative term .

Then ,\(a_n<0\) 

\(=( {a+(n-1)d} )<0\)

\(=( {50+(n-1)(-5)} )<0\)

\(=( 50-5n+5)<0\)

\(=55-5n<0\)

\(=55<5n\)

\(=5n>55\) 

\(=n>11\) 

\(\therefore n=12\)

Hence , the 12th term is the first negative term of the given AP

 

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Answer 2

12th term

\({a+(n-1)d} \\ = {50+(12-1)(-5)} \\ = 50+(-55) =-5\)