Bunuel
In the coordinate plane, Line M travels through points (9,10), (0,4), and (−9,n). What is the value of n?
A. −10
B. −6
C. −10/3
D. −2
E. −4/3
We need an equation for the line.
Any point on the line makes the equation true.
We have point (-9,n). x-coordinate is -9.
Plug -9 into line's equation. Result is the y-coordinate for that point, here called \(n\).
Slope intercept form is easy to use, thus:
\(y=mx+b\) in which \(m\) = slope and \(b\) = y-intercept
y-intercept: When \(x=0\), \(y=?\)
From (0,4), y-intercept = \(+ 4 = b\)
So far we have: \(y=mx+4\)
Use given points (9,10) and (0,4). Find slope
Slope = \(m\)
Slope=
\(\frac{rise}{run}=\frac{y_2-y_1}{x_2-x_1}=\frac{10-4}{9-0}=\frac{6}{9}=\frac{2}{3}=m\)Equation of the line
We have: \(y=\frac{2}{3}x+4\)
Coordinates\((-9,n)\): what is \(n\)?
Plug \(x=-9\) into equation
For THIS point, y-coordinate \(=n\)
\(y=((\frac{2}{3}*-9)+4)=(-6+4)=-2=n\)
\(n = -2\)
Answer D