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avatar+809 

The graphs of \(2y + x + 3 = 0\) and \(3y + ax + 2 = 0\) are perpendicular. Solve for \(a\)

 Aug 25, 2018
 #1
avatar+809 
+1

Hint: Find the slopes of both graphs, which in this case: -1/2, 2. 

 Aug 25, 2018
 #2
avatar+98091 
+2

In the form  by + ax + c  = 0....the slope is given by

 

-a / b

 

So.....  let -a/ b   be the slope of the first line   and since  perpendicular lines have negative reciprocal slopes, let  b /a  be the slope of the second line...so we have

 

-1/2   = 3 /a  

 

-2  = a / 3

 

a  = -6

 

See the graph, here : https://www.desmos.com/calculator/2rwoqegwpu

 

 

cool cool cool

 Aug 25, 2018
edited by CPhill  Aug 25, 2018
 #3
avatar+809 
+2

Yes, correct! Thanks!

mathtoo  Aug 25, 2018

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