Oh boy here we go....writing straight line equations from y=mx+b to standard form (Ax+By+C=0)

 

 

 

y=mx+b

 

i know that y=-1/2 m=1 and x=4

 

.:. -1/2=(1)(4)+b

 

-1/2=4+b

 

find common demoninator and multiply it by all

 

2(-1/2) = 2(4)+2(b)

 

-1=8+2b

 

isolate b

 

-2b=8+1

 

-2b=9

 

b= -9/2

 

as a rule though....no fractions in final answer

 

get everything on one side

 

0=x-y-9/2

 

common demoninator, multiply it by all

 

2(0)=2x-2y-2(9/2)

 

0=2x-2y-9

 

just switch so =0 is on right side....neater

 

2x-2y-9=0

 

Eh? Did I do it right...I think I did....this is how we were taught...sorry it's long I know....

It's perfect except that it's a little unorganized unless that's how your teacher wants it.