What is the graphical solution, that is, the point of intersection, of the lines \(y=-1\) and \(2x-y=9\)?
Answer and explanation
Correct answer: (4, -1)
On the first line, \(y=-1\). Substituting this in the second equation gives \(2x-(-1)=9\), or \(2x+1=9\), so \(x=4\). Therefore, the point of intersection is \((4,-1)\). In option B the coordinates are reversed, while options C and D have an incorrect \(x\)-value or \(y\)-value, respectively. Exam tip: For a horizontal line of the form \(y=\text{constant}\), the y-coordinate of the intersection is known immediately.
Frequently asked questions
What is the correct answer to this question?
(4, -1)
Why is this the correct answer?
On the first line, \(y=-1\). Substituting this in the second equation gives \(2x-(-1)=9\), or \(2x+1=9\), so \(x=4\). Therefore, the point of intersection is \((4,-1)\). In option B the coordinates are reversed, while options C and D have an incorrect \(x\)-value or \(y\)-value, respectively. Exam tip: For a horizontal line of the form \(y=\text{constant}\), the y-coordinate of the intersection is known immediately.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Pair of Linear Equations in Two Variables. Topic: Graphical method of finding solutions..
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