Question 284865
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Put each of your equations into slope-intercept form by solving each of them for *[tex \Large y] in terms of everything else.  The slope of each of the lines will then be the coefficient on *[tex \Large x].  That is to say, make your equation look like: *[tex \Large y\ =\ mx\ + b] and then the slope will be the value of *[tex \Large m]. 


If the two slopes are negative reciprocals of each other, that is to say, if *[tex \Large m_1\ =\ \frac{-1}{m_2}], then the two lines are perpendicular.  Otherwise, not.


Here is the rule:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \  L_1\ \perp\ L_2 \ \ \Leftrightarrow\ \ m_1\ =\ -\frac{1}{m_2}\ \text{ and } m_1,\, m_2\, \neq\, 0]


And, just out of curiosity, why wouldn't you want someone to tell you that you need to go back to basic arithmetic if in fact you really need to go back to basic arithmetic?


John
*[tex \LARGE e^{i\pi} + 1 = 0]
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