The points (−1,r) and (4,4) lie on a line with slope −2. Find the missing coordinate r.

Question

greatlife44 · Answer

interesting

greatlife44 · Answer

We can use this equation here $$y-y_{1} = m(x-x_{1})$$

r = y1 

then we solve for y1 

$$y_{1} = y-m(x-x_{1})$$

plug in everything 


$$4-(-2)*(4-(-1)) = 4-(-2*5) = 14$$

this means that y_{1} = 14 = r 

now let's check this

(-1,14)
(4,4)

$$m = \frac{ y-y_{1} }{ x-x_{1} } = \frac{ 14-4 }{ -1-4 } = \frac{ 10 }{ -5 } = -2 $$

anonymous · Answer

Refer to the Mathematica attachment.