Question

In this series, what number comes next? 21, 20, 18, 15, 11 . . .

Answer 1

6,0,-7,-13........ the difference increased by 1

Answer 2

Answer:

$Next \: term \: in \: the \\series = 6$

Step-by-step explanation:

Given series 21,20,18,15,11,...

Observe the series we can find ,

$First \:term (a_{1})=21$

$second\:term (a_{2})=a_{1}-1=21-1 = 20$

$a_{3}=a_{2}-2=18$

$a_{4}=a_{3}-3=18-3=15$

$a_{5}=a_{4}-4=15-4=11$

$a_{6}=a_{5}-5=11-5=6$

Here , General form of the series is ,

$a_{n}=a_{n-1}-(n-1)$

Therefore,

$Next \: term \: in \: the \\series = 6$

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