Answers

2016-07-17T05:45:53+08:00
Use this formula..

 a_{n}  a_{1} + (n-1) d

d = common difference [ 4 in this case ]

 a_{n} = 401 [ last term ]

 a_{1} = 5 [ first term ]
n=number of terms

Solve for n:

Substitute all the given:

401 = 5 + (n-1) 4 [ Subtract 5 from both sides ]

396 = (n-1) 4 [ Divide by 4 on both sides ]

99 = n-1 [ Add 1 to isolate n ] 

n=100

401 is the 100^{th} term


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