In (x=10-2y) and (x+y=7), what will be the value of (y)?
Answer and explanation
Correct answer: \(y=3\)
From the first equation, \(x=10-2y\). Substituting it into \(x+y=7\) gives \((10-2y)+y=7\), or \(10-y=7\). Hence, \(y=3\). If \(y=2\), then \(x=6\) and \(x+y=8\), so it does not satisfy the second equation. Exam tip: combine like terms carefully after substitution, especially their signs.
Frequently asked questions
What is the correct answer to this question?
\(y=3\)
Why is this the correct answer?
From the first equation, \(x=10-2y\). Substituting it into \(x+y=7\) gives \((10-2y)+y=7\), or \(10-y=7\). Hence, \(y=3\). If \(y=2\), then \(x=6\) and \(x+y=8\), so it does not satisfy the second equation. Exam tip: combine like terms carefully after substitution, especially their signs.
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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