Arithmetic Progressions

Asked by  | 13th Oct, 2009, 06:25: PM

Expert Answer:

let a and d be the first term and common diff of the A.P.

 so acc to qn,

 a+md=2[a+nd]

so

a=(m-2n)d....(i)

LHS

=a+3md

=md-2nd+3md=4md-2nd=2[(2m-n)d]

RHS

=2[a+(m+n)d]

=2[md-2nd+md+nd]

=2[2md-nd]

so

lhs=rhs

 

=2[2md-nd

Answered by  | 14th Oct, 2009, 09:07: AM

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