Class 8 Algebraic Expressions And Identities CBSE Questions & Answers

Class 8 · Algebraic Expressions And Identities

This is Mathematics Class 8 Algebraic Expressions and Identities CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
Multiply: \(\left( {{{\text{a}}^{\text{2}}} + {\text{ 2}}{{\text{c}}^{\text{2}}}} \right){\text{ }}\left( {{\text{3a }}--{\text{ 3c}}} \right)\)
  • A
    \({\text{3}}{{\text{a}}^{\text{3}}}--{\text{ 3}}{{\text{a}}^{\text{2}}}{\text{c }} + {\text{ 6}}{{\text{c}}^{\text{3}}}\)
  • B
    \({\text{3}}{{\text{a}}^{\text{3}}}--{\text{ 3}}{{\text{a}}^{\text{2}}}{\text{c }} + {\text{ 6a}}{{\text{c}}^{\text{2}}}\)
  • C
    \({\text{3}}{{\text{a}}^{\text{3}}}--{\text{ 3}}{{\text{a}}^{\text{2}}}{\text{c }} + {\text{ 6a}}{{\text{c}}^{\text{2}}}--{\text{ 6}}{{\text{c}}^{\text{3}}}\)
    Correct
  • D
    None of these
2
Simplify: (x + y) (2x – 3y + z) – (2x – 3y)z
  • A
    None of these
  • B
    \({\text{2}}{{\text{x}}^{\text{2}}}--{\text{ 3}}{{\text{y}}^{\text{2}}}--{\text{ xy }}--{\text{ xz }} + {\text{ 4yz}}\)
    Correct
  • C
    \({\text{2}}{{\text{x}}^{\text{2}}}--{\text{ 3}}{{\text{y}}^{\text{2}}}--{\text{ xy }}--{\text{ xz}}\)
  • D
    \({\text{2}}{{\text{x}}^{\text{2}}}--{\text{ 3}}{{\text{y}}^{\text{2}}}--{\text{ xy }}--{\text{ xz}}\)
3
Subtract 3x (x – 4y + 5z) from 4x (2x – 3y + 10z).
  • A
    \({\text{5}}{{\text{x}}^{\text{2}}}\)
  • B
    \({\text{5}}{{\text{x}}^{\text{2}}} + {\text{ 25xz}}\)
    Correct
  • C
    \({\text{5}}{{\text{x}}^{\text{2}}} + {\text{ 25}}\)
  • D
    None of these
4
Simplify: \({\left( {{{\text{x}}^{\text{2}}}--{\text{ }}{{\text{y}}^{\text{2}}}} \right)^{\text{2}}}\)
  • A
    \({{\text{x}}^{\text{2}}}--{\text{ 2}}{{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}} + {\text{ }}{{\text{y}}^{\text{4}}}\)
  • B
    None of these
  • C
    \({{\text{x}}^{\text{4}}}--{\text{ 2}}{{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}} + {\text{ }}{{\text{y}}^{\text{4}}}\)
    Correct
  • D
    \({{\text{x}}^{\text{3}}}--{\text{ 2}}{{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}} + {\text{ }}{{\text{y}}^{\text{4}}}\)
5
Using suitable identity find the product of . \(\left( {\frac{2}{3}x - 5} \right)\left( {\frac{2}{3}x + 5} \right)\)
  • A
    25
  • B
    \({{\text{x}}^{\text{2}}}\)
  • C
    \({\text{4}}{{\text{x}}^{\text{2}}}\)
  • D
    \(\frac{4}{9}{x^2} - 25\)
    Correct
6
Simplify 3a (4a – 5) + 3
  • A
    \({\text{12}}{{\text{a}}^{\text{2}}}--{\text{ 15a }} + {\text{ 3}}\)
    Correct
  • B
    \({\text{12}}{{\text{a}}^{\text{2}}}--{\text{ 17a }} + {\text{ 3}}\)
  • C
    \({\text{12}}{{\text{a}}^{\text{2}}}--{\text{ 15a }} + {\text{ 5}}\)
  • D
    None of these
7
Using identity \({{\text{a}}^{\text{2}}} - {\text{ }}{{\text{b}}^{{\text{2}}}} = {\text{ }}\left( {{\text{a }} + {\text{ b}}} \right){\text{ }}\left( {{\text{a }}--{\text{ b}}} \right),\)find \({\left( {{\text{1}}.0{\text{2}}} \right)^{\text{2}}}--{\text{ }}{\left( {0.{\text{98}}} \right)^{\text{2}}}.\)
  • A
    0.08
    Correct
  • B
    0.02
  • C
    None of these
  • D
    0.04
8
Using \(\left( {{\text{x }} + {\text{ a}}} \right)\left( {{\text{x }} + {\text{ b}}} \right){\text{ }} = {\text{ }}{{\text{x}}^{\text{2}}} + {\text{ }}\left( {{\text{a }} + {\text{b}}} \right){\text{ x }} + {\text{ ab}}\) find \({\text{1}}0{\text{5}} \times {\text{1}}0{\text{7}}\).
  • A
    11235
    Correct
  • B
    None of these
  • C
    12000
  • D
    11000
9
Using identity find the value of\({\left( {{\text{7}}.{\text{2}}} \right)^{\text{2}}}\).
  • A
    53
  • B
    51.84
    Correct
  • C
    55.23
  • D
    None of these
10
Using identity evaluate \({\text{297}} \times {\text{3}}0{\text{3}}\).
  • A
    89991
    Correct
  • B
    90000
  • C
    99999
  • D
    None of these
11
Using identity find the value of \({\left( {{\text{4}}.{\text{7}}} \right)^{\text{2}}}\).
  • A
    22.09
    Correct
  • B
    None of these
  • C
    23.22
  • D
    25.08
12
Simplify\({\left( {{\text{xy }} + {\text{ yz}}} \right)^{\text{2}}}-{\text{ 2}}{{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}}{\text{z}}\).
  • A
    None of these
  • B
    \({{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}} + {\text{ 2x}}{{\text{y}}^{\text{2}}}{\text{z }} + {\text{ 2}}{{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}}{\text{z}}\)
  • C
    \({{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}} + {\text{ 2x}}{{\text{y}}^{\text{2}}}{\text{z }} + {\text{ }}{{\text{y}}^{\text{2}}}{{\text{z}}^{\text{2}}}\)
  • D
    \({{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}} + {\text{ 2x}}{{\text{y}}^{\text{2}}}{\text{z }} + {\text{ }}{{\text{y}}^{\text{2}}}{{\text{z}}^{\text{2}}}-{\text{ 2}}{{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}}{\text{z}}\)
    Correct
13
Find the value of \({{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}} + {\text{ 2x}}{{\text{y}}^{\text{2}}}{\text{z }} + {\text{ }}{{\text{y}}^{\text{2}}}{{\text{z}}^{\text{2}}}--{\text{ 2}}{{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}}{\text{z}},\) when \({\text{x }} = {\text{ }} - {\text{1}},{\text{y }} = {\text{ 1 and z }} = {\text{ 2}}\).
  • A
    2
  • B
    -2
  • C
    -3
    Correct
  • D
    3
14
Which of the following is like term as\({\text{3}}{{\text{a}}^{\text{2}}}{{\text{b}}^{\text{2}}}\)?
  • A
    13b
  • B
    13a
  • C
    13ab
  • D
    \({\text{13}}{{\text{a}}^{\text{2}}}{{\text{b}}^{\text{2}}}\)
    Correct
15
Which of the following is like term as 15abc?
  • A
    8ac
  • B
    8ab
  • C
    8bc
  • D
    8abc
    Correct