Sn=m , Sm=n find Sm+n .Chapter 5 AP cbse

1.	Sn=m , Sm=n find Sm+n .Chapter 5 AP cbse
Answer» Let a is the first term and d is the common difference .(m - n) = -2a(m-n)/2 -(m-n)(m+n)/2+(m-n)d/21 = -2a/2 - (m+n)/2 + d/21 = -1/2 {2a + (m+n-1)d} ---------(1)from equation (1)S_{m+n} = -(m+n)

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