A.P QUESTION SOLVE FOR THE BRILLIANT
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Step-by-step explanation:
given, Sm=Sn
m/2[2a+(m-1)d]=n/2[2a+(n-1)d]
2am+m²d-md=2an+n²d-nd
2a(m-n)+d{m²-m-n²+n}=0
2a(m-n)+d{(m²-n²)-(m-n)}=0
2a(m-n)+d{(m-n)(m+n)-(m-n)}=0
(m-n){2a+d(m+n-1)}=0
therefor, 2a+(m+n-1)d=0
d=-2a/(m+n-1)
Sm+n=m+n/2[2a+(m+n-1)d]
=m+n/2[2a+(m+n-1)(-2a/m+n-1)]
=m+n/2[2a-2a]
=m+n/2 ×0
=0
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