Q115 / 155 · WBJEE 2019 · Mathematics

Consider the function $f(x)=\frac{x^{3}}{4}-\sin \pi x+3$

  • A
    $f(x)$ does not attain value within the interval [-2,2]
  • Correct answer
    B
    $f(x)$ takes on the value $2 \frac{1}{3}$ in the interval [-2,2]
  • Correct answer
    C
    $f(x)$ takes on the value $3 \frac{1}{4}$ in the interval [-2,2]
  • D
    $f(x)$ takes no value $\rho, 1 < p < 5$ in the interval [-2,2]

Solution

\(f(-2)=1\) and \(f(2)=5\) and \(f\) is continuous also. So intermediate value theorem, function \(f(x)\) takes all values between 1 to 5 . \(\Rightarrow \quad 2 \frac{1}{3}\) and \(3 \frac{1}{4}\) lies in 1 to 5 so option \(B, C\) are correct

Hence, the correct answer is options: 'B', 'C'.

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