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40 questions · timed · auto-graded

MCQ 11 Mark
$\frac{a}{b}+\frac{b}{a}=-1,(a, b \neq 0)$, then the value of $a^3-b^3$ is :
  • A
    $\frac{1}{2}$
  • B
    1
  • C
    -1
  • 0
Answer
Correct option: D.
0
D
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MCQ 21 Mark
If $a+b+c=0$, then $\frac{(a+b)^2}{a b}+\frac{(b+c)^2}{b c}+\frac{(c+a)^2}{a c}$ is equal to :
  • A
    0
  • B
    1
  • 3
  • D
    abc
Answer
Correct option: C.
3
C
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MCQ 41 Mark
The value of $(-28)^3+(18)^3+10^3$ is (solve without calculating the cubes):
  • A
    15120
  • -15120
  • C
    -5040
  • D
    none of these
Answer
Correct option: B.
-15120
B
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MCQ 51 Mark
Assertion (A) : $(1-3 x)^3$ can be expanded as $1-27 x^3-9 x-27 x^2$.
Reason (R) : $(a-b)^3=a^3-b^3-3 a b(a-b)$
  • A
    A is true, R is false
  • A is false, R is true
  • C
    Both A and R are true
  • D
    Both A and R are false.
Answer
Correct option: B.
A is false, R is true
B
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MCQ 61 Mark
Assertion (A) : If $x^2-2 x-1=0$, then $x^2+\frac{1}{x^2}=6$.
Reason (R) : $x^2-2 x-1$ can be written as $(x-1)^2$.
  • A is true, R is false
  • B
    A is false, R is true
  • C
    Both A and R are true
  • D
    Both A and R are false.
Answer
Correct option: A.
A is true, R is false
A
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MCQ 71 Mark
Assertion (A) : $(26)^3+(-15)^3+(-11)^3=3 \quad 26 \quad 15 \quad 11$
Reason (R): If $x+y+z=0$, then $x^3+y^3+z^3=3 x y z$
  • A
    A is true, R is false
  • B
    A is false, R is true
  • Both A and R are true
  • D
    Both A and R are false.
Answer
Correct option: C.
Both A and R are true
C
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MCQ 81 Mark
If $a \quad b+c=6$ and $a^2+b^2+c^2=38$, then the value of $a b+b c-c a$ is :
  • A
    0
  • 1
  • C
    -1
  • D
    not possible
Answer
Correct option: B.
1
B
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MCQ 91 Mark
If $l+m \quad n=9$ and $l^2+m^2+n^2=31$, then the value of $m n+n l-l m$ is :
  • -25
  • B
    25
  • C
    -2
  • D
    -5
Answer
Correct option: A.
-25
A
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MCQ 141 Mark
If $p+\frac{1}{p}=x$ and $p \quad \frac{1}{p}=y$, then the relation between $x$ and $y$ is :
  • A
    $x^2=y^2$
  • B
    $x^2+y^2=4$
  • $x^2 \quad y^2=4$
  • D
    $x y=2$
Answer
Correct option: C.
$x^2 \quad y^2=4$
C
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MCQ 191 Mark
If $x+\frac{1}{x}=5$, then $x \quad \frac{1}{x}=$
  • $\pm \sqrt{21}$
  • B
    $\pm \sqrt{29}$
  • C
    $\pm 3$
  • D
    $\pm 2$
Answer
Correct option: A.
$\pm \sqrt{21}$
A
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MCQ 201 Mark
If $p+\frac{1}{p}=\frac{5}{2}$, then $p^2+\frac{1}{p^2}=$
  • A
    $\frac{25}{4}$
  • B
    $\frac{19}{4}$
  • C
    $\frac{9}{4}$
  • $\frac{17}{4}$
Answer
Correct option: D.
$\frac{17}{4}$
D
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MCQ 231 Mark
If $a-b+c=6$ and $a^2+b^2+c^2=38$, then the value of $a b+b c-c a$ is :
  • A
    $0$
  • 1
  • C
    -1
  • D
    not possible
Answer
Correct option: B.
1
B
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MCQ 241 Mark
If $l+m-n=9$ and $l^2+m^2+n^2=31$, then the value of $m n+n l-l m$ is :
  • -25
  • B
    25
  • C
    -2
  • D
    -5
Answer
Correct option: A.
-25
A
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MCQ 291 Mark
If $p+\frac{1}{p}=x$ and $p-\frac{1}{p}=y$, then the relation between $x$ and $y$ is :
  • A
    $x^2=y^2$
  • B
    $x^2+y^2=4$
  • $x^2-y^2=4$
  • D
    $x y=2$
Answer
Correct option: C.
$x^2-y^2=4$
C
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MCQ 341 Mark
If $x+\frac{1}{x}=5$, then $x-\frac{1}{x}=$
  • $\pm \sqrt{21}$
  • B
    $\pm \sqrt{29}$
  • C
    $\pm 3$
  • D
    $\pm 2$
Answer
Correct option: A.
$\pm \sqrt{21}$
A
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MCQ 351 Mark
If $p+\frac{1}{p}=\frac{5}{2}$, then $p^2+\frac{1}{p^2}=$
  • A
    $\frac{25}{4}$
  • B
    $\frac{19}{4}$
  • C
    $\frac{9}{4}$
  • $\frac{17}{4}$
Answer
Correct option: D.
$\frac{17}{4}$
D
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MCQ 381 Mark
Assertion (A) : $(1-3 x)^2$ can be expanded as $1-27 x^3-9 x-27 x^2$.
Reason (R) : $(a-b)^3=a^3-b^3-3 a b(a-b)$
  • A
    A is true, R is false
  • A is false, R is true
  • C
    Both A and R are true
  • D
    Both A and R are false.
Answer
Correct option: B.
A is false, R is true
B
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MCQ 391 Mark
Assertion (A) : If $x^2-2 x-1=0$, then $x^2+\frac{1}{x^2}=6$.
Reason (R) : $x^2-2 x-1$ can be written as $(x-1)^2$.
  • A is true, R is false
  • B
    A is false, R is true
  • C
    Both A and R are true
  • D
    Both A and R are false.
Answer
Correct option: A.
A is true, R is false
A
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MCQ 401 Mark
Assertion (A): $(26)^3+(-15)^3+(-11)^3=3 \times 26 \times 15 \times 11$
Reason (R): If $x+y+z=0$, then $x^3+y^3+z^3=3 x y z$
  • A
    A is true, R is false
  • B
    A is false, R is true
  • Both A and R are true
  • D
    Both A and R are false.
Answer
Correct option: C.
Both A and R are true
C
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MCQ - MATHEMATICS STD 9 Questions - Vidyadip