Answers

2016-02-04T11:00:57+05:30
M(mth term)=n(nth term)
m(a+(m-1)d)=n(a+(n-1)d)
am+md(m-1)=na+nd(n-1)
a(m-n)=d(n²-n-m²+m)
a(m-n)=d(m-n-(m²-n²))
a(m-n)=d(m-n)(1-m-n)
a=d(1-m-n)

(m+n)th term=a+(m+n-1)d=d(1-m-n)+(m+n-1)d
=d(1-m-n+m+n-1)
=d*0=0
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