Answer:
m ≠1 ( all m in R except 1 )
Step-by-step explanation:
hello :
mx − y + 3 = 0.....(*)
(2m − 1)x − y + 4 = 0 ....(**)
multiply (*) by : -1 you have : -mx+y-3=0 ....(***)
(2m − 1)x − y + 4 = 0 ....(**)
add(***) and(**) : -mx+ (2m − 1)x+1 =0
(2m-m-1)x+1=0
(m-1)x = -1
this system have no solution if : m-1≠0 means : m ≠1