If Sn denotes the sum of first n terms of an A.P., prove that $${S_{12}} = 3left( {{S_8} – {S_4}} right)$$ .
If Sn denotes the sum of first n terms of an A.P., prove that $${S_{12}} = 3left( {{S_8} – {S_4}} right)$$ .
If Sn denotes the sum of first n terms of an A.P., prove that $${S_{12}} = 3left( {{S_8} – {S_4}} right)$$ .