Question

Which equation best represents the line? (10 Points)

A. y = −x + 1 over 3.
B. y = 1 over 3.x − 1
C. y = 3x + 1
D. y = 3x − 1

Answer 1

Answer: D. y = 3x − 1

Explanation:

The equation of a straight line can be represented in the slope-intercept form, y = mx + c

Where c = intercept

Slope, m =change in value of y on the vertical axis / change in value of x on the horizontal axis

change in the value of y = y2 - y1

Change in value of x = x2 -x1

y2 = final value of y

y 1 = initial value of y

x2 = final value of x

x1 = initial value of x

From the graph,

y2 = 2

y1 = - 1

x2 = 1

x1 = 0

Slope,m = (2 - - 1)/(1 - 0) = 3/1 = 3

To determine the intercept, we would substitute x = 1, y = 2 and m= 3 into y = mx + c

y = mx + c. It becomes

2 = 3 × 1 + c = 3 + c

c = 2 - 3 = - 1

The equation becomes

y = 3x - 1