Functions31 questions

Functions — JEE Maths Practice Questions & Solutions

31 questions on Functions with full step-by-step solutions, including past-year (PYQ) problems. Free to practice.

hard
If f:(0,π/n)Rf:(0,\pi/n)\to\mathbb{R} defined by f(x)=k=1n[1+sinkx]f(x)=\displaystyle\sum_{k=1}^{n}[1+\sin kx], where [x][x] denotes the integral part of xx, then range of f(x)f(x) is:
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hard
If f(x)+f(y)=f ⁣(x+y1xy)f(x)+f(y) = f\!\left(\dfrac{x+y}{1-xy}\right) for all x,yRx, y \in \mathbb{R} with xy1xy \ne 1, and limx0f(x)x=2\displaystyle\lim_{x\to 0}\dfrac{f(x)}{x} = 2, then the value of 15f(3)πf(2)\dfrac{15\,f(\sqrt{3})}{\pi\,f'(-2)} is.
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hard
If the domain of f(x)=sin1(sinx)logx+42log2 ⁣(2x13+x)f(x) = \dfrac{\sin^{-1}(\sin x)}{\sqrt{-\log_{\frac{x+4}{2}}\log_2\!\left(\frac{2x-1}{3+x}\right)}} is (a,b)(c,)(a,b)\cup(c,\infty), then the value of a+b+3ca+b+3c.
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hard
Let f(x)=[sec{x}]f(x) = [\sec\{x\}] where [x][x] and {x}\{x\} denote greatest integer and fractional parts of xx respectively, and g(x)=2x23x(k+1)+k(3k+1)g(x) = 2x^2 - 3x(k+1) + k(3k+1). Find the number of integral values of kk such that g(f(x))<0g(f(x)) < 0 for all xRx \in \mathbb{R}.
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hard
If f(x)=2010x+163165x2010f(x) = \dfrac{2010x+163}{165x-2010}, x>0x > 0, x2010165x \neq \dfrac{2010}{165}, then the least value of f(f(x))+f ⁣(f ⁣(4x))f(f(x)) + f\!\left(f\!\left(\dfrac{4}{x}\right)\right) is.
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hard
Let f(n)f(n) denote the square of the sum of the digits of natural number nn, where f2(n)=f(f(n))f^2(n) = f(f(n)), f3(n)=f(f(f(n)))f^3(n) = f(f(f(n))), and so on. Then the value of f2011(2011)f2010(2011)f2013(2011)f2012(2011)\dfrac{f^{2011}(2011)-f^{2010}(2011)}{f^{2013}(2011)-f^{2012}(2011)}.
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hard
If the range of f(x)=24{x}516{x}2f(x) = \sqrt{24\{x\}-5-16\{x\}^2}, where {}\{\cdot\} denotes fractional part, is [a,b][a,b], then the value of b2ab^2-a.
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medium
Domain of the definition f(x)=log4(5[x1][x]2)x2+x2f(x)=\dfrac{\log_{4}(5-[x-1]-[x]^{2})}{x^{2}+x-2} (where [][\cdot] denotes greatest integer function) is:
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medium
The range of the function f(x)=4cos3x8cos2x+1f(x)=4\cos^{3}x-8\cos^{2}x+1 is:
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medium
The domain of the function loge ⁣(sgn(9x2))+[x]34[x]\log_{e}\!\left(\text{sgn}(9-x^{2})\right)+\sqrt{[x]^{3}-4[x]} (where sgn is signum function and [][\cdot] is step function) is:
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medium
If [x][x] denotes the integral part of xx, then the domain of f(x)=cos1(x+[x])f(x)=\cos^{-1}(x+[x]) is:
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medium
Range of f(x)=16xC2x1+203xC4x5f(x)={}^{16-x}C_{2x-1}+{}^{20-3x}C_{4x-5} is:
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medium
The domain of the function y=2x12x3+3x2+x+sin1(log2x)y=\sqrt\dfrac{2x-1}{2x^{3}+3x^{2}+x}+\sqrt{\sin^{-1}(\log_{2}x)} is:
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medium
The domain of the function y=sinx+cosx+7xx26y=\sqrt{\sin x+\cos x}+\sqrt{7x-x^{2}-6} is:
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medium
Let f(x)=x+1x1f(x) = \dfrac{x+1}{x-1} for all x1x \neq 1. Let f1(x)=f(x)f^{-1}(x) = f(x), f2(x)=f(f(x))f^2(x) = f(f(x)), and fn(x)=f(fn1(x))f^n(x) = f(f^{n-1}(x)) for n>1n > 1. Let P=f1(2)f2(3)f3(4)f4(5)P = f^1(2)\cdot f^2(3)\cdot f^3(4)\cdot f^4(5). The number of divisors of PP.
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medium
If f(x)+f ⁣(11x)=1+xf(x) + f\!\left(1-\dfrac{1}{x}\right) = 1+x for all xR{0,1}x \in \mathbb{R} - \{0,1\},The value of 4f(2)4f(2).
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medium
If f(x)=cos ⁣(2010{x3}(2011[x2]+2012x))f(x) = \cos\!\left(2010\{x^3\}(2011^{[x^2]}+2012x)\right), xRx \in \mathbb{R}, where {}\{\cdot\} denotes fractional part and [][\cdot] denotes greatest integer function, then the value of fmaxf_{\max}.
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medium
Let ff be defined on the natural numbers as follows: f(1)=1f(1) = 1 and for n>1n > 1, f(n)=f(f(n1))+f(nf(n1))f(n) = f(f(n-1)) + f(n - f(n-1)). then the value of 130r=120f(r)\dfrac{1}{30}\displaystyle\sum_{r=1}^{20} f(r).
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medium
Let f:RRf: \mathbb{R} \to \mathbb{R} be defined as f(x)=x3+x+1f(x) = x^3 + x + 1, 1x21 \leq x \leq 2. The graph of y=g(x)y = g(x) is the reflection of the graph of y=f(x)y = f(x) through the line y=xy = x. If the domain of g(x)g(x) is [a,b][a, b], then ab|a-b| is.
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medium
Number of solutions of the equation f(x1)+f(x+1)=sinαf(x-1)+f(x+1) = \sin\alpha, 0<α<π20 < \alpha < \dfrac{\pi}{2}, where
f(x)={1x;x10;x>1f(x) = \begin{cases} 1-|x|; & |x| \leq 1 \\ 0; & |x| > 1 \end{cases}
is.
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medium
If 0xπ30\le x\le\dfrac{\pi}{3}, then range of f(x)=sec(π6x)+sec(π6+x)f(x)=\sec\left(\dfrac{\pi}{6}-x\right)+\sec\left(\dfrac{\pi}{6}+x\right) is:
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medium
A={1,2,3}A = \{1,2,3\}, B={1,3,5,7,9}B = \{1,3,5,7,9\}. Then No. of one-one functionsNo. of strictly monotonic functions\dfrac{\text{No. of one-one functions}}{\text{No. of strictly monotonic functions}}.
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medium
The number of linear functions satisfying f[x+f(x)]=x+f(x)f[x+f(x)] = x+f(x) for all xRx \in \mathbb{R} is.
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medium
f(x)=ax+bcx+df(x) = \dfrac{ax+b}{cx+d} for all xR{dc}x \in \mathbb{R}-\left\{-\dfrac{d}{c}\right\}. If f(5)=5f(5) = 5, f(13)=13f(13) = 13, and f(f(x))=xf(f(x)) = x for all xx, then the range of f(x)=R{x}f(x) = \mathbb{R}-\{x\}. Then xx.
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medium
If n(A)=4n(A) = 4, n(B)=5n(B) = 5 and the number of functions from AA to BB such that range contains exactly 3 elements is kk, then k/60k/60 is.
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medium
If aa and bb are constants, f(x)=asinx+bxcosx+2x2f(x) = a\sin x + bx\cos x + 2x^2. If f(2)=15f(2) = 15, then f(2)f(-2) is.
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medium
If f(x)=3[2x]+1000r=12008x+r[x+r]2008f(x) = 3[2x]+1000\displaystyle\sum_{r=1}^{2008}\dfrac{x+r-[x+r]}{2008}, then f(3)f(3) (where [][\cdot] is GIF) is.
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medium
The number of solutions of [sinx]+[x2π]+[2x5π]=9x10π[\sin x]+\left[\dfrac{x}{2\pi}\right]+\left[\dfrac{2x}{5\pi}\right] = \dfrac{9x}{10\pi} in the interval (30,40)(30,40) (where [][\cdot] is GIF).
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easy
If [x][x] denotes the integral part of xx, then domain of the function f(x)=3x(x1)(x2)(x3)+sin1 ⁣[3x22]f(x)=\dfrac{\sqrt{3-x}}{(x-1)(x-2)(x-3)}+\sin^{-1}\!\left[\dfrac{3x-2}{2}\right] is:
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easy
The range of the function y=[x2][x]2y=[x^{2}]-[x]^{2}, x[0,2]x\in[0,2] (where [][\cdot] denotes the integral part) is:
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easy
The number of integers in the domain of f(x)=1lncos1xf(x) = \dfrac{1}{\sqrt{\ln\cos^{-1}x}}.
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