If a line has slope (-3) and cuts the (y)-axis at ( (0,4) ), what is its equation?
Answer and explanation
Correct answer: \(y=-3x+4\)
The slope-intercept form of a line is \(y=mx+c\). Here, the slope is \(m=-3\) and the \(y\)-intercept is \(c=4\), so the equation is \(y=-3x+4\). Option A has the correct intercept but its slope is \(+3\), not \(-3\). Exam tip: from a point \((0,c)\) on the \(y\)-axis, the constant term is directly \(c\).
Frequently asked questions
What is the correct answer to this question?
\(y=-3x+4\)
Why is this the correct answer?
The slope-intercept form of a line is \(y=mx+c\). Here, the slope is \(m=-3\) and the \(y\)-intercept is \(c=4\), so the equation is \(y=-3x+4\). Option A has the correct intercept but its slope is \(+3\), not \(-3\). Exam tip: from a point \((0,c)\) on the \(y\)-axis, the constant term is directly \(c\).
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Introduction to Polynomials. Topic: Slope and y-intercept.
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