Answer:
b/a = c/d (first option)
Step-by-step explanation:
Two lines:
f(x) = a*x +b
g(x) = m*x + s
are parallel if m = a, and s ≠ b.
So the lines must have the same slope and different y-intercept.
For the graphed lines is obvious that the y-intercepts are different, so let's look at the slopes.
Remember that if a line passes through the points (x₁, y₁) and (x₂, y₂), then the slope can be written as:
slope = (y₂ - y₁)/(x₂ - x₁)
So now let's look to our lines.
The top one, passes through (-a, 0) and (0, b)
Then its slope is:
a₁ = (b - 0)/(0 - (-a)) = b/a
The bottom line passes through the points (0, -c) and (d, 0)
Then the slope will be:
m₁ = (0 - (-c))/(d - 0) = c/d
Then the lines will be only parallel if the slopes are equal, which means that we must have
b/a = c/d
The correct option is the first one.
