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A line has of a slope of -3 and Y intercept of 3 what is the X intercept of the line

2 Answers

4 votes

keeping in mind that the x-intercept is where the graph touches the x-axis, and when that happens, y = 0, thus



\bf \begin{array}ll \cline{1-1} slope-intercept~form\\ \cline{1-1} \\ y=\underset{y-intercept}{\stackrel{slope\qquad }{\stackrel{\downarrow }{m}x+\underset{\uparrow }{b}}} \\\\ \cline{1-1} \end{array}\qquad \qquad y=-3x+3 \\\\\\ \stackrel{\textit{setting y = 0}}{0=-3x+3}\implies -3=-3x\implies \cfrac{-3}{-3}=x\implies 1=x~\hfill \stackrel{\textit{x-intercept}}{(1,0)} \\\\\\ ~\hspace{34em}

User Nclarkclt
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5 votes

Answer: x-intercept = 1

Step-by-step explanation: To solve this problem, we need to remember that the y-intercept is the point where the line crosses the y-axis. So if our line has a y-intercept of 3, it crosses the y-axis up 3 units. So we start this problem by plotting the point (0,3) on y-axis and we can label that point A.

From there, our slope of -3 can be thought of as -3/1 so we go down 3 units and to the right 1 unit and we plot point B. Notice that point B happens to lie on the x-axis at (1,0) and it's important to understand that the x-intercept is the point where the line crosses the x-axis.

Since our line crosses the x-axis at the point (1,0), it as an x-intercept of 1. If you're given a y-intercept and a slope like you are in this problem, you won't always be able to determine the x-intercept but things work out nicely here because point B happens to lie on the x-axis.

I provided an image with the graph and my work as well.

A line has of a slope of -3 and Y intercept of 3 what is the X intercept of the line-example-1
User NA Slacker
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