Question in-the

1.3 Linear Equations in Two Variables - Writing equations from data/points
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In the xy-plane, line k passes through the points 0,-5 and 1,-1. Which equation defines line k ?

A.

y = - x + 1 4

B.

y=14x-5

C.

y = - x + 4

D.

y = 4 x - 5

In the xy -plane, line k passes through the points 0 , - 5 and 1

Hard-difficulty · SAT Math · Linear Equations in Two Variables — Writing equations from data/points. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice D is correct. An equation defining a line in the xy-plane can be written in the form y = m x + b , where m represents the slope and 0,b represents the y-intercept of the line. It’s given that line k passes through the point 0,-5; therefore, b = -5 . The slope, m , of a line can be found using any two points on the line, x1,y1 and x2,y2, and the slope formula m=y2-y1x2-x1. Substituting the points 0,-5 and 1,-1 for x1,y1 and x2,y2, respectively, in the slope formula yields m=-1--51-0, or m = 4 . Substituting 4 for m and -5 for b in the equation y = m x + b yields y = 4 x - 5

Choice A is incorrect and may result from conceptual or calculation errors.

Choice B is incorrect and may result from conceptual or calculation errors.

Choice C is incorrect and may result from conceptual or calculation errors.