मराठी

Which term of the sequence 114, 109, 104, ... is the first negative term?

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प्रश्न

Which term of the sequence 114, 109, 104, ... is the first negative term?

 
बेरीज
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उत्तर

Here, A.P is 114, 109, 104, ..

So, first term, a = 114 

Now,

Common difference (d) =  a1 - a

= 109 - 114 

= -5

Now, we need to find the first negative term,

 an < 0

114 + (n-1) (-5) < 0

     114 - 5n + 5 < 0

          119 - 5n < 0

                 5n > 119 

Further simplifying, we get,

n > `119/5`

n > 23 `4/5`

n ≥ 24                                  (as n is a natural m=number) 

Thus, n = 24 

Therefore, the first negative term is the  24th term of the given A.P.

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पाठ 5: Arithmetic Progressions - Exercise 5.7 [पृष्ठ ५६]

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आर.डी. शर्मा Mathematics [English] Class 10
पाठ 5 Arithmetic Progressions
Exercise 5.7 | Q 3 | पृष्ठ ५६

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