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All questions of Linear Equations in one Variable for Class 8 Exam

What is the first step to solve the equation 2x + 5 = 11?
  • a)
    Add 5 to both sides
  • b)
    Subtract 5 from both sides
  • c)
    Multiply both sides by 2
  • d)
    Divide both sides by 2
Correct answer is option 'B'. Can you explain this answer?

EduRev Class 8 answered
To isolate the variable in the equation 2x + 5 = 11, the first step is to subtract 5 from both sides, resulting in 2x = 6. This allows us to further solve for x.

How do you represent consecutive multiples of 3 starting with x?
  • a)
    x, x + 1, x + 2
  • b)
    x, x + 3, x + 6
  • c)
    x, x + 2, x + 4
  • d)
    x, x + 3, x + 9
Correct answer is option 'B'. Can you explain this answer?

Sakshi Chauhan answered
Understanding Consecutive Multiples
To represent consecutive multiples of 3 starting with a number x, we must remember what a multiple of 3 is. A multiple of a number is obtained by multiplying that number by an integer.
Definition of Multiples of 3
- The first multiple of 3 after x can be represented as:
- x + (3 - (x mod 3)) if x is not already a multiple of 3.
- If x is a multiple of 3, then the first multiple is simply x.
Consecutive Multiples of 3
- Once we have the starting point, the next consecutive multiples of 3 can be calculated by simply adding 3 repeatedly.
Option Analysis
Let's analyze option B: x, x + 3, x + 6.
- First term:
- The initial term is x.
- Second term:
- The second term is x + 3, which is the next multiple of 3 after x.
- Third term:
- The third term is x + 6, which is 3 added to the previous term (x + 3), making it 2 multiples of 3 after x.
Why Other Options are Incorrect
- Option A: x, x + 1, x + 2
- These are not multiples of 3.
- Option C: x, x + 2, x + 4
- These numbers skip multiples of 3.
- Option D: x, x + 3, x + 9
- This skips the multiple x + 6, making it incorrect.
Conclusion
Thus, the correct representation of consecutive multiples of 3 starting with x is option B: x, x + 3, x + 6.

What is the solution to the equation 3y = 9?
  • a)
    y = 3
  • b)
    y = 5
  • c)
    y = 6
  • d)
    y = 2
Correct answer is option 'A'. Can you explain this answer?

EduRev Class 8 answered
To solve 3y = 9, divide both sides by 3, resulting in y = 3. This is a straightforward solution that showcases the basic principle of isolating the variable.

What is the equation formed if x represents the first of two consecutive odd numbers and the sum is 36?
  • a)
    x + (x + 4) = 36
  • b)
    x + (x + 1) = 36
  • c)
    x + (x + 2) = 36
  • d)
    x + (x + 3) = 36
Correct answer is option 'C'. Can you explain this answer?

The equation x + (x + 2) = 36 is formed to represent the sum of two consecutive odd numbers. This equation reflects the relationship between the first and the second odd number.

If the perimeter of a rectangle is 26 cm, what is its new perimeter when each side is increased by x cm?
  • a)
    26 + 4x
  • b)
    52 + 4x
  • c)
    52 cm
  • d)
    26 + 2x
Correct answer is option 'A'. Can you explain this answer?

The new perimeter after increasing each side by x cm would be calculated as 2[(8 + x) + (5 + x)], which simplifies to 26 + 4x. This reflects the increase in perimeter due to the adjustment in dimensions.

What would the equation be for the situation where a man is 24 years older than his son?
  • a)
    x + 24 = y
  • b)
    y - x = 24
  • c)
    y + 24 = x
  • d)
    x - y = 24
Correct answer is option 'A'. Can you explain this answer?

EduRev Class 8 answered
If we let x represent the age of the son and y represent the age of the man, the equation y = x + 24 correctly expresses that the man is 24 years older than his son. This relationship is crucial for solving age-related problems.

In the equation 5z - 10 = 0, what is the root of the equation?
  • a)
    z = 1
  • b)
    z = 10
  • c)
    z = 0
  • d)
    z = 2
Correct answer is option 'D'. Can you explain this answer?

EduRev Class 8 answered
By adding 10 to both sides of the equation 5z - 10 = 0, we find that 5z = 10. Dividing both sides by 5 gives z = 2, which is the root of the equation.

Which of the following represents consecutive even numbers starting from x?
  • a)
    x + 1, x + 3, x + 5
  • b)
    x, x + 2, x + 4
  • c)
    x, x + 1, x + 2
  • d)
    x, x + 1, x + 3
Correct answer is option 'B'. Can you explain this answer?

EduRev Class 8 answered
Consecutive even numbers can be represented as x, x + 2, x + 4, where x is an even integer. This shows the difference of 2 between each successive even number.

If a linear equation has a root of 4, what does this indicate about the equation?
  • a)
    It has no solutions.
  • b)
    It has multiple solutions.
  • c)
    The equation is satisfied when x = 4.
  • d)
    The equation is invalid.
Correct answer is option 'C'. Can you explain this answer?

A root of 4 means that when x is substituted with 4 in the equation, both sides of the equation are equal. This indicates that x = 4 satisfies the equation, confirming it as a valid solution.

What is the new length of a rectangle if its original length is 8 cm and each side is increased by 6.5 cm?
  • a)
    10 cm
  • b)
    8 cm
  • c)
    14.5 cm
  • d)
    20 cm
Correct answer is option 'C'. Can you explain this answer?

EduRev Class 8 answered
When the original length of 8 cm is increased by 6.5 cm, the new length becomes 8 + 6.5 = 14.5 cm. This calculation reflects the adjustment made to the rectangle's dimensions.

What is the general form of a linear equation in one variable?
  • a)
    ax + b = 0
  • b)
    ax^2 + b = 0
  • c)
    ax^2 + bx + c = 0
  • d)
    ax + b = c
Correct answer is option 'A'. Can you explain this answer?

A linear equation in one variable is expressed in the form ax + b = 0, where 'a' and 'b' are constants, and 'a' cannot equal zero. This form signifies that the equation represents a straight line when graphed.

When solving the equation 2x - 3 = 7, what is the correct operation to isolate x?
  • a)
    Subtract 3 from both sides
  • b)
    Divide both sides by 2
  • c)
    Multiply both sides by 2
  • d)
    Add 3 to both sides
Correct answer is option 'D'. Can you explain this answer?

EduRev Class 8 answered
To isolate x in the equation 2x - 3 = 7, the correct first step is to add 3 to both sides, resulting in 2x = 10. This prepares for the next step of dividing by 2 to find x.

What is the solution to the equation 2x - 1 = 3?
  • a)
    x = 3
  • b)
    x = 4
  • c)
    x = 1
  • d)
    x = 2
Correct answer is option 'D'. Can you explain this answer?

To solve the equation 2x - 1 = 3, first add 1 to both sides, yielding 2x = 4. Then, dividing by 2 gives x = 2. This solution illustrates the step-by-step process of isolating the variable.

In the equation 2x = 10, what is the next step after dividing both sides by 2?
  • a)
    x = 10
  • b)
    x = 20
  • c)
    x = 2
  • d)
    x = 5
Correct answer is option 'D'. Can you explain this answer?

After dividing both sides of 2x = 10 by 2, we obtain x = 5. This is the solution that satisfies the equation, demonstrating the isolation of the variable.

What is the solution to the equation 4x - 8 = 0?
  • a)
    x = 4
  • b)
    x = 0
  • c)
    x = 2
  • d)
    x = -2
Correct answer is option 'C'. Can you explain this answer?

To solve 4x - 8 = 0, first add 8 to both sides to get 4x = 8, and then divide by 4, resulting in x = 2. This is the value that satisfies the equation.

What is the process to solve a word problem involving linear equations?
  • a)
    Solve the problem without forming an equation
  • b)
    Ignore the details of the problem
  • c)
    Identify the known and unknown quantities, then form an equation
  • d)
    Guess the answer
Correct answer is option 'C'. Can you explain this answer?

The correct approach to solving word problems is to carefully identify the known and unknown quantities and then form an appropriate equation based on the relationships described. This structured method ensures a logical solution.

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