If the sum of m terms of an AP. is the same as that sum of its n terms

1.	If the sum of m terms of an AP. is the same as that sum of its n terms, show
Answer» m/2 (2a+(m-1)d)=n/2 (2a+(n-1)d) 2am+(m-1)md=2an+(n-1)nd 2a(m-n)+d (m^2-n^2-m+n)=0 2a+d (m+n-1)=0 Show that the sum of its (m+n) terms is zero

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