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Mary
Mary

Secondary 1 chevron_right Maths chevron_right Hong Kong

General term of sequence
2,-4,6,-8,10,...

Date Posted: 6 years ago
Views: 547
J
J
6 years ago
General term = (-1)^(n+1)2n
= -2n(-1)ⁿ

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Kam Tian Qiao
Kam Tian Qiao's answer
14 answers (Tutor Details)
1st
From the question you can observe that , the number increase by 2 , and the sign is alternating , so number increase by 2 can be represent by 2n , and alternating sign can represent by (-1)^n , combine both u get 2n*(-1)^n , substitute n =1,2,3,4 into it u get -2,+4,-6,+8 right? So add negative sign to it ,becomes -2n*(-1)^n , therefore u will get +2,-4,+6,-8 when substitute n=1,2,3,4