1
WB JEE 2026
MCQ (Single Correct Answer)
+2
-0.5
Change Language

If $f$ be a real valued function defined for all real numbers $x$ such that for some fixed $a>0$, it satisfies $f(x+a)=\frac{1}{2}+\sqrt{f(x)-(f(x))^2} \forall x$, then $f(x)$ is periodic with period

A

a

B

4a

C

$\frac{\mathrm{a}}{2}$

D

2 a

2
WB JEE 2026
MCQ (Single Correct Answer)
+2
-0.5
Change Language

Four natural numbers selected at random are multiplied together, then the probability that the digit in the unit's place in the product be $1,3,7$ or 9 is

A

$\frac{16}{625}$

B

$\frac{18}{625}$

C

$\frac{4}{625}$

D

$\frac{5}{625}$

3
WB JEE 2026
MCQ (Single Correct Answer)
+2
-0.5
Change Language

Let $f(x)$ be a real valued $f$ unction which is monotonic and differentiable. Then for any reals a and $b, \int_{f(a)}^{f(b)} 2 x\left\{b-f^{-1}(x)\right\} d x=$

A

$\int_a^b\left(f^2(x)-f^2(a)\right) d x$

B

$\int_a^b(f(x)-f(a))^2 d x$

C

$\int_a^b\left(b f^2(x)-a f^2(a)\right) d x$

D

$\mathrm{bf}^2(\mathrm{~b})+\mathrm{f}^{-1}(\mathrm{a})$

4
WB JEE 2026
MCQ (Single Correct Answer)
+2
-0.5
Change Language

Tangent at a point $P_1$ (other than $(0,0)$ ) on the curve $y=x^3$ meets the curve again at $P_2$. The tangent at $P_2$ meets the curve at $\mathrm{P}_3$ and so on. Then the abscissae of $\mathrm{P}_1, \mathrm{P}_2, \mathrm{P}_3, \ldots, \mathrm{P}_{\mathrm{n}}$ form

A

an A.P. with common difference 1

B

an H.P. with common difference $\frac{1}{2}$

C

a G.P. with common ratio 2

D

a G.P. with common ratio (-2)