Tag: introduction to sets

Questions Related to introduction to sets

If $\alpha$ and $\beta$ are the polynomial  $f(x)=x^2-5x+k$ such that $\alpha-\beta=1$, then value of k is 

  1. $8$

  2. $6$

  3. $\dfrac{13}{2}$

  4. $4$


Correct Option: A

If $y^2 = ax^2 +bx+c$, then $y^2 \dfrac{d^2y}{dx^2}$ is

  1. a constant function

  2. a function of x only

  3. a function of y only

  4. a function of both x and y


Correct Option: A

If $fxln\left(1+\dfrac{1}{x}\right)dx=p(x)ln\left(1+\dfrac{1}{x}\right)+\dfrac{1}{2}x-\dfrac{1}{2}ln(1+x)+c$, being arbitary costant, then

  1. $p(X)=\dfrac{1}{2}x^{2}$

  2. $p(x)=0$

  3. $p(x)=1$

  4. $none\ of\ these$


Correct Option: A

Let $f(x)$ is cubic polynomial with real coefficient such that $f''(3) = 0, f'(5) = 0$. If $f(3) = 1$ and $f(5) = -3$, then $f(1)$ is equal to

  1. $2$

  2. $3$

  3. $5$

  4. $6$


Correct Option: A

$f (x) = x^4 - 10x^3 + 35x^2 - 50x + c$ is a constant. the number of real roots of . f (x) = 0 and 
f'' (x) = 0 are respectively 

  1. 1 , 0

  2. 3, 2

  3. 1 , 2

  4. 3 , 0


Correct Option: A

Let $\displaystyle f(x)=ax^{2}+bx+c,$ where $a,b,c$ are rational, and $f: Z\rightarrow Z,$ where $Z$ is the set of integers. Then $a+b$ is

  1. a negative integer

  2. an integer

  3. nonintegral rational number

  4. none of these


Correct Option: B
Explanation:

$f:Z \rightarrow Z$ is defined as $f(x)=ax^2+bx+c$

which implies for integer inputs, the function gives integer outputs.

$ \Rightarrow f(0)=c=Z _1$ ...(1) (where $Z _1$ is some integer)

Similarly, $f(1)=a+b+c=Z _2$ ...(2) (where $Z _2$ is some integer)

(2) - (1) gives $a+b =Z _2-Z _1$, which is also an integer.

The positive integers $x$ for which $f(x)=x^{3}-8x^{2}+20x-13$ is a prime is

  1. $2$

  2. $3$

  3. $4$

  4. $5$


Correct Option: A

If $f\quad \left( x \right) ={ x }^{ 2 }+2bx+{ 2c }^{ 2 }\quad and\quad g\quad (x)\quad ={ -x }^{ 2 }\quad -2cx+{ b }^{ 2 }\quad are\quad such\quad that\quad min\quad f\quad (x)\quad >\quad max\quad g\quad (x),\quad then$ relation between b and c, is

  1. none relation

  2. 0 < c < b/2

  3. $\left| c \right| <\frac { \left| b \right| }{ \sqrt { 2 } } $

  4. $\left| c \right| >\sqrt { 2 } \left| b \right| $


Correct Option: A

If $f(x)$ is a polynomial function satisfying $f(x)f\left(\dfrac{1}{x}\right)=f(x)+\left(\dfrac{1}{x}\right)$ and $f(3)=28$, then $f(4)=$

  1. $63$

  2. $65$

  3. $66$

  4. $27$


Correct Option: A

If $f\left(x\right)$ is a polynomial such that $ f\left(a\right) f\left(b\right)<0$, then number of zeros lieing between $a$ and $b$ is 

  1. $one$

  2. $at least one$

  3. $two$

  4. $at most 2$


Correct Option: A