For (7x+4y=2) and (3x-4y=18), what is the value of (x-y) in the solution?
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Answer and explanation
Correct answer: 5
Adding the two equations eliminates y because the terms 4y and -4y cancel: 10x = 20, so x = 2. Substituting x = 2 into 7x + 4y = 2 gives 14 + 4y = 2, hence y = -3. Therefore, x - y = 2 - (-3) = 5. Exam tip: Add equations directly when one variable has equal and opposite coefficients.
Frequently asked questions
What is the correct answer to this question?
5
Why is this the correct answer?
Adding the two equations eliminates y because the terms 4y and -4y cancel: 10x = 20, so x = 2. Substituting x = 2 into 7x + 4y = 2 gives 14 + 4y = 2, hence y = -3. Therefore, x - y = 2 - (-3) = 5. Exam tip: Add equations directly when one variable has equal and opposite coefficients.
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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