Answer:
2x - y = 0
Step-by-step explanation:
The equation of a line in slope- intercept form is
y = mx + c ( m is the slope and c the y- intercept )
y = 2x - 1 ← is in slope- intercept form
with slope m = 2
Parallel lines have equal slopes, thus
y = 2x + c ← is the partial equation
To find c substitute (1, 2) into the partial equation
2 = 2 + c ⇒ c = 2 - 2 = 0
y = 2x ← equation in slope- intercept form
Subtract y from both sides
0 = 2x - y , that is
2x - y = 0 ← equation in standard form
