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45
MCQ (Single Correct Answer)

If $f: N \rightarrow R$ be the function defined by $f(x)=\frac{2 x-1}{2}$ and $g: Q \rightarrow R$ be another function defined by $g(x)=x+2$. Then, $(g \circ f) \frac{3}{2}$ is

A
1
B
1
C
$\frac{7}{2}$
D
None of these
46
MCQ (Single Correct Answer)

If $f: R \rightarrow R$ be defined by $f(x)=\left\{\begin{array}{l}2 x: x>3 \\ x^2: 1< x \leq 3 \\ 3 x: x \leq 1\end{array}\right.$ Then, $f(-1)+f(2)+f(4)$ is

A
9
B
14
C
5
D
None of these
47
MCQ (Single Correct Answer)

If $f: R \rightarrow R$ be given by $f(x)=\tan x$, then $f^{-1}(1)$ is

A
$\frac{\pi}{4}$
B
$\left\{n \pi+\frac{\pi}{4}: n \in Z\right\}$
C
Does not exist
D
None of these
48

Let the relation $R$ be defined in $N$ by $a R b$, if $2 a+3 b=30$. Then, $R=$ ..........

Explanation

$$\begin{aligned} \text{Given that,}\quad 2 a+3 b & =30 \\ 3 b & =30-2 a \\ b & =\frac{30-2 a}{3} \end{aligned}$$

$$\begin{aligned} \text{For}\quad & a=3, b=8 \\ & a=6, b=6 \\ & a=9, b=4 \\ & a=12, b=2 \\ & R=\{(3,8),(6,6),(9,4),(12,2)\} \end{aligned}$$

49

If the relation $R$ be defined on the set $A=\{1,2,3,4,5\}$ by $R=\left\{(a, b):\left|a^2-b^2\right|< 8\right\}$. Then, $R$ is given by ............ .

Explanation

Given,

$$\begin{aligned} & A=\{1,2,3,4,5\}, \\ & R=\left\{(a, b):\left|a^2-b^2\right|<8\right\} \\ & R=\{(1,1),(1,2),(2,1),(2,2),(2,3),(3,2),(3,3),(4,3),(3,4),(4,4),(5,5)\} \end{aligned}$$