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If `x, 2x+ 2, 3x + 3 `are in `G.P. ,` then the fourth term is (A) `27` (B) `-27` (C)`13.5` (D)`-13.5`A. `27`B. `-27`C. `13.5`D. `-13.5` |
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Answer» Correct Answer - D If `x, 2x+2,3x+3` are …………. Given that `x, 2x+2, 3x+3` are in G.P. Therefore, `(2x+2)^(2)= x(3x+3)` `implies x^(2)+5x+4 = 0` `implies (x+4)(x+1) = 0` `implies x = -1 -4` Now first term `a = x`, second trem `ar = 2(x+1)` `implies r= (2(x+1))/(x)`, then `4^(th)` term `= ar^(3)` `= x[(2(x+1))/(x)]^(-3) = (8)/(x^(2))(x+1)^(3)` Putting `x = -4`, We get `T_(4)= (8)/(16)(-3)^(3) = -(27)/(2)= - 13.5` |
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