Mathematics · 2021
JEE Main · 24 February 2021, Shift 2 · Q69
Let f be a twice differentiable function defined on R such that f(0)=1, f^′(0)=2 and f^′(x) ≠ 0 for all x ∈ R. If |f(x), f^′(x); f^′(x), f^′ ′(x)|…
Let $\displaystyle f$ be a twice differentiable function defined on $\displaystyle \mathbf{R}$ such that $\displaystyle f(0)=1, f^{\prime}(0)=2$ and $\displaystyle f^{\prime}(x) \neq 0$ for all $\displaystyle x \in \mathbf{R}$. If $\displaystyle \left|\begin{array}{cc}f(x) & f^{\prime}(x) \\ f^{\prime}(x) & f^{\prime \prime}(x)\end{array}\right|=0$, for all $\displaystyle x \in \mathbf{R}$, then the value of $\displaystyle f(1)$ lies in the interval:
Official answer
(3)
$\displaystyle (6,9)$
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JEE Main 2021 Mathematics question, with the answer from NTA’s final answer key. Where our answers come from.