Q48 / 90 · KVPY 2017 (19 Nov SB/SX) · Mathematics

Define a function $f(x)=\frac{16 x^{2}-96 x+153}{x-3}$ for all real $x \neq 3$. The least positive value of $f(x)$ is

  • A
    16
  • B
    18
  • C
    22
  • Correct answer
    D
    24

Solution

$y=\frac{16 x^{2}-96 x+153}{x-3}$ make it quadratic in $\mathrm{x}$ $\begin{array}{l} 16 x^{2}-x(96+y)+(153+3 y)=0 \\ D \geq 0 \end{array}$ Solve $y^{2}-576 \geq 0$ $\mathrm{y} \in(-\infty,-24] \cup[24, \infty)$ So, least positive is 24

Hence, the correct answer is option: 'D'.

More Functions Questions