an equation of the line that contains the origin and the point (1,2) is?

Question

The answer choices are-

 

A. y=2x

B. 2y=x

C. y=x-1

D. y=2x+1

E. y/2 = x-1

Answer 1

Sarah,

 

The correct answer is A. Here is the reasoning. The line passes through (0,0) and (1,2). The slope is

 

m = (2 − 0)/(1 − 0) = 2.

 

(You could also see this by drawing the two points and a slope triangle and use the rise/run idea of slope.)

 

In the slope-intercept form, y = mx + b, you now know that m = 2 and b = 0, so the answer is

 

y = 2x + 0 or y = 2x.