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The 4th term of an A.P. is zero. Prove that the 25th term of the A.P. is threetimes its 11th term. |
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Answer» Given a4= 0That is (a + 3d) = 0⇒ a = - 3d → (1)nth term of AP is given by an= a + (n – 1)da11= a + 10d = – 3d + 10d = 7d [From (1)]a25= a+ 24d = – 3d + 24d = 21d [From (1)] = 3 x 7dHence a25= 3 x a11 |
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