Solve the equation -2+5+8……+x =155

Asked by poojathally | 6th Mar, 2010, 09:54: AM

Expert Answer:

2+5+8……+x  = 155  

LHS is an AP with first term 2 and common difference 3

Sum to n terms is [ n/2(4+(n-1)3]=155

n(1+3n)=155x2

3n2+n-310=0

Solve this equation to get n

use 2+3(n-1) to get x

Answered by  | 6th Mar, 2010, 12:27: PM

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