Class 10 Maths MCQs on Substitution and Elimination Methods
CBSE Class 10 Mathematics – Substitution & Elimination Methods MCQs
Chapter 3: Pair of Linear Equations in Two Variables
Based on NCERT Curriculum
As per Latest CBSE Board Examination Pattern
1. In substitution method, first step is to:
Correct Answer: C
Explanation: In substitution method, we first express one variable (say x) in terms of y (or vice versa) and substitute it into the other equation.
Explanation: In substitution method, we first express one variable (say x) in terms of y (or vice versa) and substitute it into the other equation.
2. Solve using substitution: x = y + 2 and x + y = 8. Value of y is:
Correct Answer: B
Explanation: Substitute x = y + 2 into second equation:
(y + 2) + y = 8 ⇒ 2y + 2 = 8 ⇒ 2y = 6 ⇒ y = 3.
Explanation: Substitute x = y + 2 into second equation:
(y + 2) + y = 8 ⇒ 2y + 2 = 8 ⇒ 2y = 6 ⇒ y = 3.
3. Using elimination, we make coefficients:
Correct Answer: A
Explanation: In elimination method, we multiply equations to make coefficients of one variable equal (or opposites) so it can be eliminated.
Explanation: In elimination method, we multiply equations to make coefficients of one variable equal (or opposites) so it can be eliminated.
4. Solve: x + y = 5 and x − y = 1. Value of x is:
Correct Answer: B
Explanation: Add both equations:
2x = 6 ⇒ x = 3.
Explanation: Add both equations:
2x = 6 ⇒ x = 3.
5. Solve: x + y = 5 and x − y = 1. Value of y is:
Correct Answer: B
Explanation: Substitute x = 3 in first equation:
3 + y = 5 ⇒ y = 2.
Explanation: Substitute x = 3 in first equation:
3 + y = 5 ⇒ y = 2.
6. In elimination method, if coefficients are already equal and opposite, we:
Correct Answer: B
Explanation: If coefficients are equal and opposite, adding equations eliminates that variable.
Explanation: If coefficients are equal and opposite, adding equations eliminates that variable.
7. Solve: 2x + y = 7 and 2x − y = 1. Value of x is:
Correct Answer: B
Explanation: Add equations:
4x = 8 ⇒ x = 2.
Explanation: Add equations:
4x = 8 ⇒ x = 2.
8. Solve: 2x + y = 7 and 2x − y = 1. Value of y is:
Correct Answer: C
Explanation: Substitute x = 2 into first equation:
4 + y = 7 ⇒ y = 3.
Explanation: Substitute x = 2 into first equation:
4 + y = 7 ⇒ y = 3.
9. Solve: 3x + 2y = 12 and x + y = 5. Value of x is:
Correct Answer: A
Explanation: From second equation: x = 5 − y.
Substitute:
3(5 − y) + 2y = 12 ⇒ 15 − 3y + 2y = 12 ⇒ y = 3 ⇒ x = 2.
Explanation: From second equation: x = 5 − y.
Substitute:
3(5 − y) + 2y = 12 ⇒ 15 − 3y + 2y = 12 ⇒ y = 3 ⇒ x = 2.
10. Solve: 3x + 2y = 12 and x + y = 5. Value of y is:
Correct Answer: B
Explanation: From calculation above, y = 3.
Explanation: From calculation above, y = 3.
11. Elimination method is preferred when:
Correct Answer: B
Explanation: If coefficients can be easily made equal, elimination is quicker.
Explanation: If coefficients can be easily made equal, elimination is quicker.
12. Substitution method is useful when:
Correct Answer: A
Explanation: If one equation easily gives x or y in terms of other, substitution is convenient.
Explanation: If one equation easily gives x or y in terms of other, substitution is convenient.
13. After elimination, we get equation in:
Correct Answer: B
Explanation: Eliminating one variable leaves equation in one variable.
Explanation: Eliminating one variable leaves equation in one variable.
14. If elimination gives 0 = 0, system has:
Correct Answer: C
Explanation: 0 = 0 indicates coincident equations ⇒ infinite solutions.
Explanation: 0 = 0 indicates coincident equations ⇒ infinite solutions.
15. If elimination gives 0 = 5, system has:
Correct Answer: C
Explanation: 0 = 5 is false ⇒ inconsistent system ⇒ no solution.
Explanation: 0 = 5 is false ⇒ inconsistent system ⇒ no solution.
16. Solution of consistent independent system is:
Correct Answer: A
Explanation: Independent system has unique solution.
Explanation: Independent system has unique solution.
17. Solve: x − y = 2 and x + y = 6. Value of x is:
Correct Answer: C
Explanation: Add equations:
2x = 8 ⇒ x = 4.
Explanation: Add equations:
2x = 8 ⇒ x = 4.
18. For above system, value of y is:
Correct Answer: B
Explanation: Substitute x = 4:
4 − y = 2 ⇒ y = 2.
Explanation: Substitute x = 4:
4 − y = 2 ⇒ y = 2.
19. Substitution method reduces system to:
Correct Answer: A
Explanation: After substitution, equation contains only one variable.
Explanation: After substitution, equation contains only one variable.
20. Elimination method mainly involves:
Correct Answer: B
Explanation: By making coefficients equal and adding/subtracting, one variable is eliminated.
Explanation: By making coefficients equal and adding/subtracting, one variable is eliminated.
