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All questions of Linear Equations for SSS 1 Exam

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If am ≠ bl, then the system of equations, ax + by = c, lx + my = n
  • a)
    has a unique solution
  • b)
    has no solution
  • c)
    has infinitely many solutions
  • d)
    may or may not have a solution
Correct answer is option 'A'. Can you explain this answer?

Vivek Rana answered
If am ≠ bl, then the equations ax+by=c, lx+my=n has a unique solution.
Given,
Pair of lines represented by the equations
ax + by = c
lx + my = n
For unique solution
For infinite solutions
For no solution
Given,
This can be transformed into
Therefore, If am ≠ bl, then the equations ax+by=c, lx+my=n has a unique solution.

The pair of equations 3x + 4y = k, 9x + 12y = 6 has infinitely many solutions if –
  • a)
    k = 2
  • b)
    k = 6
  • c)
    k = 6
  • d)
    k = 3
Correct answer is option 'A'. Can you explain this answer?

Naina Sharma answered
An equation has infinitely many solutions when the lines are coincident.
The lines are coincident when 
So 3x + 4y = k, 9x + 12y = 6 are coincident when

The pair of equations x = 2 and y = – 3 has
  • a)
    no solution
  • b)
    two solutions
  • c)
    infinitely many solutions
  • d)
    one solution
Correct answer is option 'D'. Can you explain this answer?

Here a unique solution of each variable of a pair of linear equations is given, therefore, it has one solution of a system of linear quations.

The pair of equations y = 0 and y = - 7 has
  • a)
    one solution
  • b)
    two solutions
  • c)
    infinitely many solutions
  • d)
    no solution
Correct answer is option 'D'. Can you explain this answer?

Gaurav Kumar answered
The equation are y=0 and y=-7
y=0 is on the x-axis and y=-7 is the line parallel to the x-axes at a distance 7 units from y=0
The line will be parallel
if we try to solve these equations we get 0=7 which is absurd.
So the equations are inconsistent.
Therefore there is no solution.

The sum of two numbers is 45 and one is twice the other. What is the smaller number?​
  • a)
    30
  • b)
    35
  • c)
    15
  • d)
    25
Correct answer is option 'C'. Can you explain this answer?

To solve this problem, we can use algebraic equations. Let's assume that the smaller number is x.

Given that one number is twice the other, we can express the larger number in terms of the smaller number as:

Larger number = 2x

And the sum of the two numbers is 45, so we can write the equation:

x + 2x = 45

Simplifying the equation, we have:

3x = 45

Dividing both sides of the equation by 3, we get:

x = 15

Therefore, the smaller number is 15.

So, option C, 15, is the correct answer.

The sum of the digits of a two-digit number is 9. If 27 is added to it, the digit of number get reversed. The number is
  • a)
    25
  • b)
    72
  • c)
    63
  • d)
    36
Correct answer is option 'D'. Can you explain this answer?

Avinash Patel answered
Lets,
First digit number = x
Second digit number = y
Number = (x+10y)
A/Q,
x + y = 9 ...................... (i)
A/Q,
(x+10y) = (10x+y) + 27
x + 10y = 10x + y +27
9x - 9y = 27
9(x - y) = 27
x - y = 27/9
x - y = 3 ......................... (ii)
Equation (i) and (ii) we get,
x = 3
Putting the value of x in eq.(i)
we get,
y = 6
Number = (10x +y)
= 10 x 3 + 6
= 30 + 6
= 36

The pair of linear equations x + y + 10 = 0 and x + y – 7 = 0 has:
  • a)
    One solution
  • b)
    Infinitely many solutions
  • c)
    No solutions
  • d)
    Two solutions
Correct answer is option 'C'. Can you explain this answer?

Gaurav Kumar answered
We have a1, a2 the coefficients of x2,b1 and b2 coefficients of x and c1 and c2 the constant terms.So,a1a2=b1b2c1c2which is a case of parallel lines which which never meet. So there are no solutions obtainable for these equations.

Find the solution to the following system of linear equations: 
x-2y = 6 
2x+y = 17​
  • a)
    (8,1)
  • b)
    (12,3)
  • c)
    (1,2)
  • d)
    (10,2)
Correct answer is option 'A'. Can you explain this answer?

Thor Kss answered
X-2y=6 and 2x+y=17

by eliminating
x-2y=6*2
2x+y=17*1

2x will be cancelled
then y will be 1
and when we value of y in equation 1
we get x=8

 One equation of a pair of dependent linear equations is -5x + 7y = 2, the second equation can be :
  • a)
    -10x + 14y + 4 = 0
  • b)
    -10x – 14x + 4 =
  • c)
    10x – 14y = -4
  • d)
    10x + 14y + 4 =0
Correct answer is option 'C'. Can you explain this answer?

Vikram Kapoor answered
If a  system of two linear equation is consistent system and has an infinite number of solutions, it is dependent . When you graph the equations, both equations represent the same line.So we have which is satisfied by 10x – 14y = -4 only.

The pair of linear equations 2x + 3y = 5 and 4x + 6y = 10 is
  • a)
    inconsistent
  • b)
    Both
  • c)
    consistent
  • d)
    none of these
Correct answer is option 'C'. Can you explain this answer?

Amit Sharma answered
a1 / a2 = b1 / b2 = c1 / c2
2/4 = 3/6 = 5/10
1/2 = 1/2 = 1/2
So, a1 / a2 = b1 / b2 = c1 / c2 
When these are equal then it is consistent.
Therefore option (C) is correct .

 Find the solution to the following system of linear equations: 0.2x + 0.3y = 1.2
0.1x – 0.1y = 0.1​
  • a)
    (1,2)
  • b)
    (2,3)
  • c)
    (3,2)
  • d)
    (2,1)
Correct answer is option 'C'. Can you explain this answer?

Arun Sharma answered
0.2x + 0.3y = 1.2
2x+3y=12   …..(1)
0.1x – 0.1y = 0.1​x-y=1  ….(2)
From (2), x=1+y
Substituting the values of x in (1)
2(1+y)+3y=12
2+2y+3y=12
5y=10
y=2
x=1+2= 3

Which of the following points lie on the line  3x+2y=5 ?
  • a)
    (1, 1)
  • b)
    (0, 1)
  • c)
    (1, 0)
  • d)
    (2, 1)
Correct answer is option 'A'. Can you explain this answer?

Krishna Iyer answered
When we are given only one equation and two variables we assume values for one variable and find the values for the other variable.
3x+2y=5
Let x=1
3*1+2y=5
2y=2
y=1 hence (1,1) lies on the line.

The sum of the digits of a two digit number is 12. The number obtained by reversing its digits exceeds the given number by 18. Then the number is_____
  • a)
    75
  • b)
    25
  • c)
    52
  • d)
    57
Correct answer is option 'D'. Can you explain this answer?

Neha Patel answered
Let us assume x and y are the two digits of the number
Therefore, two-digit number is = 10x + y and the reversed number = 10y + x
Given:
x + y = 12
y = 12 – x  (1)
Also given:
10y + x - 10x – y = 18
9y – 9x = 18
y – x = 2    (2)
Substitute the value of y from eqn 1 in eqn 2
12 – x – x = 2
12 – 2x = 2
2x = 10
x = 5
Therefore, y = 12 – x = 12 – 5 = 7
Therefore, the two-digit number is 10x + y = (10*5) + 7 = 57

The pair of linear equations 2x + 5y = k, kx + 15y = 18 has infinitely many solutions if –
  • a)
    k = 3
  • b)
    k = 6
  • c)
    k = 9
  • d)
    k = 18
Correct answer is option 'B'. Can you explain this answer?

Vivek Rana answered
An equation has infinitely many solutions when the lines are coincident.
The lines are coincident when 
So 2x + 5y = k, kx + 15y = 18 are coincident when

In elimination method _____________ is an important condition.​
  • a)
    Equating either of the coefficients
  • b)
    Equating only the y coefficient.
  • c)
    Equating only the x co-efficient.
  • d)
    Equating both the coefficients.
Correct answer is option 'A'. Can you explain this answer?

Rajiv Gupta answered
Elimination Method (by Equating Coefficients)
There is another method of eliminating a variable, than often used method i. e --------Suppose you are to solve
23x - 17y + 11=0
------(1)
and
31x + 13y - 57 = 0
-------(2)
Now expressing x in terms of y would involve division by 23 or 31. Express y in terms of x, it would involve division by 17 or 13. You know that multiplication is more convenient than division, better to convert the division process into a multiplication process.
Multiplying the first equation by 13 viz., coefficient of y in (2), and second by 17 viz., coefficient of y in (1), you will get an equivalent system of equations. The new system has the advantage that y has the same numerical coefficient 17x13 in both the equations. When you add these new equations, the terms containing y would cancel out as these have opposite signs and the same numerical coefficient. Thus, y has been eliminated. Now proceed as before, and solve the system. This method of elimination is also called elimination by equating coefficients for obvious reasons.

Example: Solve the following system of equations using the elimination method by equating coefficients:
11x - 5y + 61 = 0 (1)
3x - 20y - 2 = 0
(2)
Solution: Let us multiply equation (1) by 3 and equation (2) by 11. This gives
33x - 15y + 183 = 0
(3)
and
33x - 220y - 22 = 0
(4)
Subtracting (4) from (3), you will get 205y + 205 = 0
, or
y = - 1
Substituting this value of y in equation (2), you will get
3x - 20 * (- 1) - 2 = 0
or
3x = -18
or
x = - 6
Thus, the required solution is
x = - 6 and y = -1.
Now you should verify; substitute x = - 6 and y = -1 in the given equations, you will notice both the equations are satisfied. Hence, the solution is correct

Six years hence a man's age will be three times the age of his son and three years ago he was nine times as old as his son. The present age of the man is –
  • a)
    28 years
  • b)
    30 years
  • c)
    32 years
  • d)
    34 years
Correct answer is option 'B'. Can you explain this answer?

Raghav Bansal answered
Let the present age of man is x and of son is y.
Six years hence,
Man’s age =x+6
Son’s age=y+6
Man’s age is 3 times son’s age
x+6=3(y+6)
x+6=3y+18
x=3y+12    …...1
Three years ago,
Man’s age =x-3
Son’s age=y-3
Man’s age was 9 times as of son
x-3=9(y-3)
x-3=9y-27
x=9y-24   ….2
From 1 and 2
3y+12=9y-24
6y=36
y=6
x=3*6+12=18+12=30 years

The value of x in mx + ny = c; nx – ny = c + 1 is​
  • a)
    x = (m + n) / (c + 1)
  • b)
    x = (2c + 1) / (m + n)
  • c)
    x = m + n
  • d)
    x = 2c + 1
Correct answer is option 'B'. Can you explain this answer?

Mansi desai answered
To find the value of x in the equation mx + ny = c, we need more information or another equation. The equation nx = 0 does not provide enough information to solve for x.

Can you explain the answer of this question below:

The area of the triangle formed by the lines 2x + y = 6, 2x – y + 2 = 0 and the x – axis is

  • A:

    15sq. units

  • B:

    8sq. units

  • C:

    10sq. units

  • D:

    12sq. units

The answer is b.

Arun Sharma answered
Here are the two solutions of each of the given equations. 2x+y = 6
2x+y=0


The area bounded by the given lines and x−axis has been shaded in the graph. 

The Index of Coincidence for English language is approximately
  • a)
    0.068
  • b)
    0.038
  • c)
    0.065
  • d)
    0.048
Correct answer is option 'C'. Can you explain this answer?

Yes actually you said option C is correct it is actually correct but the actual answer is different

actual answer for index of coincide of English language is 0.0 667

index of coincide is a technique to find the probability of the repeating letters in an encrypted text

the index of coincide value is calculated on the basis of the probability of occurrence of a specified letter and the probability of comparing it to the same letter from the second text





so this is my answer for index of coincide of English language is 0.0667 but you have given that C is correct option
To sketch the graph of pair of linear equations in two variables, we draw two lines representing the equations.

If both the lines intersect at a point, then there exists a unique solution to the pair of linear equations. In such a case, the pair of linear equations is said to be consistent.

 For what value of ‘K’ will the system of equations: 3x + y = 1, (2K – 1) x + (K – 1) y = 2K + 1 have no solution
  • a)
    3
  • b)
    2
  • c)
    1
  • d)
    -2
Correct answer is option 'B'. Can you explain this answer?

Krishna Iyer answered
 is a case of parallel lines which never meet. So there are no solutions obtainable for these equations. So equations are inconsistent
3x + y = 1, (2K – 1) x + (K – 1) y = 2K + 1
b1=1,b2=k-1,c1=-1,c2=-2k-1

The pair of linear equations 2kx + 5y = 7, 6x – 5y = 11 has a unique solution if –
  • a)
    k ≠ -3
  • b)
    k = 3
  • c)
    k = 5
  • d)
    k = -5
Correct answer is option 'A'. Can you explain this answer?

Rohit Sharma answered
Given :
2 k x + 5 y – 7 = 0  ...( i )
6 x – 5 y – 1 = 0   ... ( ii )
Pair of linear equations has a unique solution.
We know for unique solution.
Comparing from ( i ) and ( ii ) we have
Put these values in formula.
Thus we get answer many values of k but leaving k ≠ -3.

Can you explain the answer of this question below:

The sum of the numerator and denominator of a fraction is 18. If the denominator is increased by 2, the fraction reduces to 1/3. The fraction is

  • A:

    7/11

  • B:

    -5/13

  • C:

    -7/11

  • D:

    5/13

The answer is d.

Rahul Kapoor answered
Let the numer be x & denom be y..
x+y= 18....(1)
x/y+2 =1/3
3x=y+2
x=(y+2)/3
put this value in eq 1
x+y=18
(y+2)/3+y=18
(y+2+3y= 18x3
4y+2 =54
4y=54-2
4y= 52
y= 52/4
y= 13
put the value of y in eq 1
x+y=18
x+ 13=18
x= 18- 13
x= 5
Hence req. fraction = x/ y = 5/13

Can you explain the answer of this question below:

The pair of equations y = 0 and y = -7 has :

  • A:

    no solution

  • B:

    infinitely many solutions

  • C:

    one solution

  • D:

    two solutions

The answer is a.

Raghav Bansal answered
y=0 is x-axis… since every point has y=0. y=-7 is a line parallel to x-axis passing through x=0,y=-7. So the two lines are parallel to each other and are inconsistent which means that it has no solutions because it will never meet.

The sum of two numbers is 35 and their difference is 13. The numbers are
  • a)
    24 and 11
  • b)
    20 and 15
  • c)
    25 and 12
  • d)
    11 and 24
Correct answer is option 'A'. Can you explain this answer?

Pranav Menon answered
Let the numbers be x and .y. 
According to question, x+y = 35 ………(i) and x−y = 13 ………..(ii)
Adding eq. (i) and (ii), we get  2x = 48 ⇒ x = 24
Putting the value of x in eq. (i), we get 12+y = 35 ⇒ y = 13
Therefore, the numbers are 24 and 13.

 If x + 2y = 5 & x – 2y = 7, then the value of x & y is: -
  • a)
    x = 6 & y = 3
  • b)
    x = 12 & y = -1/2
  • c)
    x = 6 & y = -1/2
  • d)
    None of the above
Correct answer is option 'C'. Can you explain this answer?

Roshni jain answered
Solution:

Given, x + 2y = 5 ...(1)

and x + 2y = 7 ...(2)

Subtracting Equation (1) from Equation (2), we get

( x + 2y ) - ( x + 2y ) = 7 - 5

⇒ 0 = 2

The above equation is not satisfied for any value of x and y. Therefore, such values of x and y do not exist.

Hence, the correct option is (d) None of the above.

If the sum of the ages of a father and his son in years is 65 and twice the difference of their ages in years is 50, then the age of the father is –
  • a)
    45 years
  • b)
    40 years
  • c)
    50 years
  • d)
    55 years
Correct answer is option 'A'. Can you explain this answer?



Learn how to form quadratic equations and how to solve them by going through this document of important definitions and formulas for quadratic equations:
https://p1.edurev.in/studytube/Important-definitions-and-formulas-Quadratic-Equat/b324db73-b4c1-42a0-9b27-228a123e101b_t

If x = a, y = b is the solution of the equations x – y = 2 and x + y = 4, then the values of a and b are, respectively.
  • a)
    3 and 1
  • b)
    -1 and -3
  • c)
    3 and 5
  • d)
    5 and 3
Correct answer is option 'A'. Can you explain this answer?

Arun Yadav answered
Since, x = a and y = b is the solution of the equations x – y = 2 and x+ y = 4, then these values will satisfy that equations
a-b= 2                ,..(i)
and  a + b = 4 … (ii)
On adding Eqs. (i) and (ii), we get
2a = 6
a = 3 and b = 1

Which of the following pairs of equations represent inconsistent system?​
  • a)
    3x – y = -8 3x – y = 24
  • b)
    5x – y = 10 10x – 2y = 20
  • c)
    3x – 2y = 8 2x + 3y = 1
  • d)
    lx – y = m x + my = l
Correct answer is option 'A'. Can you explain this answer?

Amit Sharma answered
is a case of parallel lines which never meet. So there are no solutions obtainable for these equations. So equations are inconsistent.
3x – y = -8 ,3x – y = 24
3x – y +8=0 ,3x – y -24=0

So, Therefore the equations are inconsistent.

Chapter doubts & questions for Linear Equations - Mathematics for SSS 1 2024 is part of SSS 1 exam preparation. The chapters have been prepared according to the SSS 1 exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for SSS 1 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

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