1
WB JEE 2026
MCQ (Single Correct Answer)
+1
-0.25
Change Language

Consider a function $f(x)$ which has exactly two roots at $x=a$. If $\mathop {\lim }\limits_{x \to a}\left(\frac{\lambda f^{\prime}(x)}{f(x)}-\frac{1}{x-a}\right)=m(\neq 0)$, then the value of $\lambda$ ix

A

2

B

1

C

$\frac{1}{2}$

D

$\frac{1}{4}$

2
WB JEE 2026
MCQ (Single Correct Answer)
+1
-0.25
Change Language

If $a=\mathop {\lim }\limits_{n \to \infty } \cos ^{2 n} x,(x=n \pi)$ and $b=\mathop {\lim }\limits_{n \to \infty } \cos ^{2 n} x,(x \neq n \pi)$, then numerical value of the area of the triangle whose vertices are (a, b), (-2, 1) and (2, 1) is

A

2

B

4

C

1

D

$\frac{1}{2}$

3
WB JEE 2026
MCQ (Single Correct Answer)
+1
-0.25
Change Language

For a real number $y$, consider $(y)$ denotes the greatest integer less than or equal to $y$. If $f(x)=\frac{\tan (\pi[x-\pi])}{1+[x]^2}$, then

A

$\mathrm{f}^{\prime}(\mathrm{x})$ exists for all x

B

$\mathrm{f}^{\prime}(\mathrm{x})$ does not exist

C

$f^{\prime}(1)=\frac{\pi}{4}$

D

$\mathrm{f}^{\prime}(1)=-\frac{\pi}{4}$

4
WB JEE 2026
MCQ (Single Correct Answer)
+2
-0
Change Language

If $f(x)$ is differentiable for all $x \in \mathbb{R}$ and satisfies the relation

$x=\mathop {\lim }\limits_{n \to \infty }\frac{\left[1^2(f(x))^x\right]+\left[2^2(f(x))^x\right]+\ldots+\left[n^2(f(x))^x\right]}{n^3}$ where [.] denotes the greatest integer function, then $f^{\prime}(x)=$

A

$\frac{1}{3 x^2} \log x$

B

$3 x^{\frac{1}{x}}(1-\log 3 x)$

C

$(3 x)^{\frac{1}{x}}\left[\frac{1-\log 3 x}{x^2}\right]$

D

$(3 x)^{\frac{1}{x}}\left[\frac{\log 3 x-1}{x^2}\right]$

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