In algebra it is fully possible for x to equal to zero. After you have 2x, just divide both sides by two, so it would be 2 divided by 0 and than you would have x=0 and that would be your final answer.
2x + 1 = 4x +1
-2x +1 = 1
-2x = 0
divide by -2
x=0
Distance formula : d = sqrt (x2 - x1)^2 + (y2 - y1)^2
(11,4)(10,5)
d = sqrt (10 - 11)^2 + (5 - 4)^2
d = sqrt (-1^2) + (1^2)
d = sqrt (1 + 1)
d = sqrt 2
d = 1.41 <===