Question

which equation represents the graphA. y= 1/2x - 1 B. y= -1/2x - 1 C. y= 2x - 1 D. -2x - 1

Answer 1

The general form of the equation of a line is:

y=mx+b

Where m is the slope of the line and b the intercept, which is the y-coordinate of the point where the line crosses the y-axis.

Since the line intersects the y-axis at the point (0,-1), then b = -1

We can calculate the slope of the line (m) by means of the formula:

$m=\frac{y2-y1}{x2-x1}$

Where (x1,y1) and (x2,y2) are two points of the line. we can take the points (0,-1) and (-1,1), then the slope of the line is:

$m=\frac{1-(-1)}{-1-0}=\frac{1+1}{-1}=\frac{2}{-1}=-2$

Then m = -2

The equation that represents this line is option D

y= -2x - 1