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avatar+96 

Line $l_1$ represents the graph of $3x + 4y = -14$. Line $l_2$ passes through the point $(-5,7)$, and is perpendicular to line $l_1$. If line $l_2$ represents the graph of $y=mx +b$, then find $m+b$.

 

Thank you in advance

 Mar 22, 2021
 #1
avatar+121003 
+2

3x  +4y  =  -14

 

4y  = -3x   - 14

 

y  = -(3/4)x - 14/4

 

y=  -(3/4)x  -7/2

 

The slope of this line =  -3/4

 

The  slope ofthe perpendicular line =  4/3

 

So...using the  slope and point (-5, 7)    we have

 

y = (4/3) ( x - - 5)  +  7

 

y= (4/3)( x + 5)  + 7

 

y= (4/3)x  + 20/3  + 21/3

 

y= (4/3)x  + 41/3

 

m + b =   4/3  + 41/3  =  45/3  =  15

 

Here's a graph :  https://www.desmos.com/calculator/uxagghudww

 

cool cool cool

 Mar 22, 2021
 #2
avatar+96 
+1

That is correct! Thank you so much.

 

Can you help with my other question too please?

Immaguest  Mar 22, 2021
edited by Immaguest  Mar 22, 2021

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