If five times the fifth term of an AP is equal to seven times the seventh term of the AP, then what is the twelfth term?

Question

Accepted Answer

T5 = a + 4d, T7 = a + 6d ∴ 5(a + 4d) = 7(a + 6d) ⇒ 5a + 20d = 7a + 42d ⇒ a = -11d ⇒ T12 = a + 11d = - 11d + 11d = 0 So, the twelfth term is 0.

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