Solving (x+2y=18) and (4x-y=9) by substitution, what is the value of (y)?
Answer and explanation
Correct answer: 7
From the first equation, x=18-2y. Substituting this in the second equation gives 4(18-2y)-y=9, or 72-9y=9. Thus, 9y=63 and y=7. Therefore, option B is correct. Exam tip: In the substitution method, express one variable in terms of the other and substitute it into the remaining equation carefully.
Frequently asked questions
What is the correct answer to this question?
7
Why is this the correct answer?
From the first equation, x=18-2y. Substituting this in the second equation gives 4(18-2y)-y=9, or 72-9y=9. Thus, 9y=63 and y=7. Therefore, option B is correct. Exam tip: In the substitution method, express one variable in terms of the other and substitute it into the remaining equation carefully.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Pair of Linear Equations in Two Variables. Topic: Algebraic methods: Substitution method and Elimination method..
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