$\mathrm{A}(1,15), \mathrm{B}(3,-12), \mathrm{C}(6,12)$ are three consecutive turning points of a continuous…

$\mathrm{A}(1,15), \mathrm{B}(3,-12), \mathrm{C}(6,12)$ are three consecutive turning points of a continuous curve $y=f(x)$. If $f(x)=0$ only for $x=\alpha$ and $x=\beta$, then $|\beta-\alpha| < $
  1. $27$
  2. $2$
  3. $5$
  4. $25$

Solution

Given that $\mathrm{A}(1,15), \mathrm{B}(3,-12), \mathrm{C}(6,12)$ are threeconsecutive turning points of continuous curve $y=f(x)$ and intersect $x$-axis at $x=\alpha$, and $x=\beta$.
It is clear from graph is $\begin{aligned} & 1 < \alpha < 3 \text { and } 3 < \beta < 6 \Rightarrow-\alpha < -1 \text { and } \beta < 6 \\ & \Rightarrow|\beta-\alpha| < 6-1 \Rightarrow|\beta-\alpha| < 5 . \end{aligned}$

Asked in: AP EAMCET 2023 (16 May Shift 2)

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