What is the slope of the line that is perpendicular to y = 2x – 3?

Question

hartnn · Answer

can you find slope of this line ? 
y= 2x-3
?

deadshot · Answer

the slope is 0 for y=2x-3

hartnn · Answer

nopes, how ? 

compare it with, y= mx+c 
where m= slope

deadshot · Answer

oh, so then the slope is 2?

hartnn · Answer

yes

now product of slope of perpendicular lines =-1

so, to get the slope of perpendicular line, you just take negative reciprocal of this slope

deadshot · Answer

so then the slope of the perpendicular line would be -2?

anonymous · Answer

$$
0=\begin{bmatrix}
1 \ m
\end{bmatrix}
\cdot 

\begin{bmatrix}
1 \ m'
\end{bmatrix} \implies  1 + mm' = 0 \implies mm' = -1 \implies m' = -\frac 1 m
$$

hartnn · Answer

you forgot to do reciprocal ?

deadshot · Answer

yeah, It's been a while since I've done this

anonymous · Answer

So if $m$ is the slope of a line, a line who is perpendicular has slope $m' = -\frac 1 m$.

hartnn · Answer

what is the reciprocal of 2 ?

deadshot · Answer

ok, so then the reciprocal of 2 would be $$- \frac{ 1 }{ 2 }$$ right?

hartnn · Answer

reciprocal of 2 is 1/2

so, the slope of line will be -1/2
yes, correct.

hartnn · Answer

slope of perpendicular line**

deadshot · Answer

Okay, thanks!

hartnn · Answer

welcome ^_^