Maple...
Maple tells us that the exact solution of the equation
y ' = y - x  that has y(0) = 2 is   y(x) = x + 1 + ex
and so we have y(1) = 4.718281828.
So the Euler method result is pretty close (within 10%). We
could do better by decreasing Dx, but of course then we'd
need more steps to reach x = 1.
You'll get to try a couple of these on this week's homework.