The roots of the equation $x^3-14 x^2+56 x-64=0$ are in

The roots of the equation $x^3-14 x^2+56 x-64=0$ are in
  1. AGP
  2. $\mathrm{HP}$
  3. $\mathrm{AP}$
  4. GP

Solution

We have, $\begin{aligned} & x^3-14 x^2+56 x-64=0 \\ \text { at } x & =2,8-14.4+56.2-64 \\ = & 8-56+112-64=0\end{aligned}$ Ther efore, the given equation can be written as $\begin{array}{r}x^2(x-2)-12 x(x-2)+32(x-2)=0 \\ (x-2)\left(x^2-12 x+32\right)=0 \\ (x-2)(x-4)(x-8)=0\end{array}$ The roots are $2,4,8$, which are in GP.

Asked in: AP EAMCET 2001

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