Parallel lines have the same slope. So if a line has a slope of 2, a line parallel to it also has a slope of 2.
This is a quadratic equation, which is also a polynomial. Polynomials all have the domain (-infinity, +infinity).
As for the range: You can see from the graph that the smallest y-value is -2. Thus, the range is [-2, infinity).
Answer:
y = 2x
the formula for linear equations are y = mx+c,
where m is the gradient,
and c is the y-intercept
to find m (the gradient):
1. pick to points on the graph (eg. -2,-4 and 2,4)
2 substitute the values into the formula for gradient y2-y1/x2-x1.
m = y2-y1/x1-x2
= -4 -4/-2-2
= -8/-4
= 2
to find c (y-intercept):
- the y-intercept is where the graph cuts the y axis
- in this graph, the y-intercept is 0
hence,
c = 0
substitute m = 2 and c = 0 to y = mx+c,
y = 2x + 0
y = 2x
hence, the equation that best represents the relationship shown in the graph is y = 2x.